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Unit 3/4 – Moles / StoichiometryChemistry Review

Unit 3/4 – Moles / StoichiometryFormula Writing, Naming & Writing Chemical Compound Formulas, Chemical Equations, Mole Interpretation, Stoichiometry

Moles and Stoichiometry 1. A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can only be broken down by chemical means.

2. Chemical compounds can be represented by a specific formula and assigned a name based on the IUPAC system.

3. Types of chemical formulas include empirical, molecular, and structural. Empirical formulas show elements in their simplest whole number ratios. This may or may not be the same as the

molecular formula. Molecular formulas show the actual number of atoms per element in a single molecule. Structural formulas show the number of each type of atom as well as their physical arrangement.

4. All chemical reactions show a conservation of mass, energy and charge.

5. A balanced chemical equation represents conservation of atoms.

6. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction.

7. The formula mass of a substance is the sum of the atomic masses of its atoms. The molar mass (gram formula mass) equals the mass of one mole of that substance.

8. The percent composition by mass of each element in a compound can be calculated mathematically.

9. Types of chemical reactions include synthesis, decomposition single replacement, and double replacement.

June 20131

Unit 3/4 – Moles / StoichiometryJanuary 2013June 2012

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Unit 3/4 – Moles / Stoichiometry

10: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge.17: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system37: 3.3viii Calculate the formula mass and gram-formula mass51: 3.1ppThe concentration of a solution may be expressed in molarity (M), percent by volume, percent by mass, or parts per million (ppm)52: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement53: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction.54: 3.2a A physical change results in the rearrangement of existing particles in a substance. A chemical change results in the formation of different substances with changed properties.55: 3.3ix Determine the number of moles of a substance, given its mass3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation68: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically.

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January 2012

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17: 3.4e Equal volumes of gases at the same temperature and pressure contain an equal number of particles.33: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement36: M1.1C – Use algebraic and geometric representations to describe and compare data by recognizing and converting various scales of measurement37: 4.1d Energy released or absorbed during a chemical reaction (heat of reaction) is equal to the difference between the potential energy of the products and potential energy of the reactants66: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system.74: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction.76: 3.3ix Determine the number of moles of a substance, given its mass77: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically.78: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound.

June 2011

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7: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge.9: 3.3e The formula mass of a substance is the sum of the atomic masses of its atoms. The molar mass (gram-formula mass) of a substance equals one mole of that substance.

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Unit 3/4 – Moles / Stoichiometry34: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system.35: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically37: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass38: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound.39: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement41: 3.2a A physical change results in the rearrangement of existing particles in a substance. A chemical change results in the formation of different substances with changed properties.46: 3.2d An oxidation-reduction (redox) reaction involves the transfer of electrons (e-).49: 5.3c Energy released during nuclear reactions is much greater than the energy released during chemical reactions.66: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction.

January 2011

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10: 3.3e The formula mass of a substance is the sum of the atomic masses of its atoms. The molar mass (gram-formula mass) of a substance equals one mole of that substance.39: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement47: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction54: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass55: Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement69: Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement71: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation76: 3.2i Oxidation numbers (states) can be assigned to atoms and ions. Changes in oxidation numbers indicate that oxidation and reduction have occurred.

August 2010

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7: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction.9: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically.18: 3.4e Equal volumes of gases at the same temperature and pressure contain an equal number of particles36: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass70: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement71: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass

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Unit 3/4 – Moles / Stoichiometry72: 3.3viii Calculate the formula mass and gram-formula mass

June 2010

17: 3.4e Equal volumes of gases at the same temperature and pressure contain an equal number of particles.34:36: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound56: M1.1B – Use algebraic and geometric representations to describe and compare data by measuring and recording experimental data and use data in calculations such as using appropriate equations and significant digits73: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement75: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance

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Unit 3/4 – Moles / Stoichiometry3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass

January 2010

9: 3.3e The formula mass of a substance is the sum of the atomic masses of its atoms. The molar mass (gram-formula mass) of a substance equals one mole of that substance10: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement22: 3.4e Equal volumes of gases at the same temperature and pressure contain an equal number of particles23: 5.2m Intermolecular forces created by the unequal distribution of charge result in varying degrees of attraction between molecules. Hydrogen bonding is an example of a strong intermolecular force36: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass

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Unit 3/4 – Moles / Stoichiometry3.3ix Determine the number of moles of a substance, given its mass 37: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound68: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically

August 2009

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35: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement36: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound40: 3.1ppThe concentration of a solution may be expressed in molarity (M), percent by volume, percent by mass, or parts per million (ppm)52: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation55: 3.3vi Determine the mass of a given number of moles of a substance56: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge57: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction79: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically

June 2009

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7: 3.3vi Determine the mass of a given number of moles of a substance33: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound34: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement74: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction79: M1.1C – Use algebraic and geometric representations to describe and compare data by recognizing and converting various scales of measurement80: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass81: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement83: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically

January 2009

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11: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge17: 3.4e Equal volumes of gases at the same temperature and pressure contain an equal number of particles22: 3.3b In a redox reaction the number of electrons lost is equal to the number of electrons gained36: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound54: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass 69: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction

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Unit 3/4 – Moles / Stoichiometry71: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass76: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically78: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically

August 2008

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Unit 3/4 – Moles / Stoichiometry34: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge.3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction35: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically63: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction74: 3.3vi Determine the mass of a given number of moles of a substance75: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation76: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound

June 2008

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7: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge19: 3.4e Equal volumes of gases at the same temperature and pressure contain an equal number of particles35: M1.1B – Use algebraic and geometric representations to describe and compare data by measuring and recording experimental data and use data in calculations such as calculating percent error36: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance

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Unit 3/4 – Moles / Stoichiometry3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass 42: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation47: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound56: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass67: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation3.3vi Determine the mass of a given number of moles of a substance3.3viii Calculate the formula mass and gram-formula mass3.3ix Determine the number of moles of a substance, given its mass74: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction

January 2008

34: 3.3viii Calculate the formula mass and gram-formula mass54: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound77: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically78: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement79: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation

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August 2007

10: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction12: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system17: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system.35: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound70: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement71: 3.3viii Calculate the formula mass and gram-formula mass72: 3.1cc A compound is a substance composed of two or more different elements that are chemically

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Unit 3/4 – Moles / Stoichiometrycombined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system

June 2007

7: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system9: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system36: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system38: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound55: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically59: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction

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Unit 3/4 – Moles / Stoichiometry60: 3.2i Oxidation numbers (states) can be assigned to atoms and ions. Changes in oxidation numbers indicate that oxidation and reduction have occurred.

January 2007

10: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction17: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system18: 3.1t The proportions of components in a mixture can be varied. Each component in a mixture retains its original properties.35: 3.3viii Calculate the formula mass and gram-formula mass36: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation

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Unit 3/4 – Moles / Stoichiometry54: M1.1B – Use algebraic and geometric representations to describe and compare data by measuring and recording experimental data and use data in calculations such as calculating percent error

August 2006

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6: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system.9: 5.2d Electron-dot diagrams (Lewis structures) can represent the valence electron arrangement in elements, compounds, and ions37: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically38: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation44: 4.1b Chemical and physical changes can be exothermic or endothermic.82: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction83: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement84: 3.3ix Determine the number of moles of a substance, given its mass85: 3.2x Use an activity series to determine whether a redox reaction is spontaneous

June 2006

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6: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system7: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction

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Unit 3/4 – Moles / Stoichiometry33: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound35: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically51: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system52: 3.2x Use an activity series to determine whether a redox reaction is spontaneous69: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction70: 3.4ii Solve problems, using the combined gas laws

January 2006

8: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system10: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction33: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically36: 3.3viii Calculate the formula mass and gram-formula mass57: 3.3ix Determine the number of moles of a substance, given its mass

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Unit 3/4 – Moles / Stoichiometry75: 3.3viii Calculate the formula mass and gram-formula mass76: 3.1ppThe concentration of a solution may be expressed in molarity (M), percent by volume, percent by mass, or parts per million (ppm)77: 3.1xxx Describe the preparation of a solution, given the molarity

August 2005

9: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system31: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically

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Unit 3/4 – Moles / Stoichiometry36: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation38: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement48: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement51: 3.3viii Calculate the formula mass and gram-formula mass52: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound68: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction69: 3.3ix Determine the number of moles of a substance, given its mass70: Density equation – General math standard

June 2005

9: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system36: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system37: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound39: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically54: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation

January 2005

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8: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system9: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically19: 3.4e Equal volumes of gases at the same temperature and pressure contain an equal number of particles34: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound35: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge.3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction68: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system69: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically

August 2004

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8: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge29: 3.1zz Titration is a laboratory process in which a volume of a solution of known concentration is used to determine the concentration of another solution.37: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound50: M1.1B – Use algebraic and geometric representations to describe and compare data by measuring and recording experimental data and use data in calculations such as using appropriate equations and significant digits52: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation53: 3.1ppThe concentration of a solution may be expressed in molarity (M), percent by volume, percent by mass, or parts per million (ppm)61: 3.3viii Calculate the formula mass and gram-formula mass62: 3.3vi Determine the mass of a given number of moles of a substance66: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction

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Unit 3/4 – Moles / Stoichiometry67: 4.1c Energy released or absorbed during a chemical reaction can be represented by a potential energy diagram68: 3.2i Oxidation numbers (states) can be assigned to atoms and ions. Changes in oxidation numbers indicate that oxidation and reduction have occurred69: M1.1C – Use algebraic and geometric representations to describe and compare data by recognizing and converting various scales of measurement

June 2004

7: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction8: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically38: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound

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Unit 3/4 – Moles / Stoichiometry51: 3.2b Types of chemical reactions include synthesis, decomposition, single replacement, and double replacement52: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge.3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction53: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation81: 5.2d Electron-dot diagrams (Lewis structures) can represent the valence electron arrangement in elements, compounds, and ions82: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system83: 3.1xxix Calculate solution concentration in molarity (M), percent mass, and parts per million (ppm)84: S3.4 Using results of the test and through public discussion, revise the explanation and contemplate additional research

January 2004

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6: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system36: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound39: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge.3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction51: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction52: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation75: 3.3viii Calculate the formula mass and gram-formula mass76: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically

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August 2003

6: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system8: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically10: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge39: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation42: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound

June 2003

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8: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound10: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically19: 3.1cc A compound is a substance composed of two or more different elements that are chemically combined in a fixed proportion. A chemical compound can be broken down by chemical means. A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC system20: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation59: 3.3a In all chemical reactions there is a conservation of mass, energy, and charge

January 2003

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8: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically13: 3.3d The empirical formula of a compound is the simplest whole-number ratio of atoms of the elements in a compound. It may be different from the molecular formula, which is the actual ratio of atoms in a molecule of that compound22: 3.3f The percent composition by mass of each element in a compound can be calculated mathematically42: 3.3iv Calculate simple mole-mole stoichiometry problems, given a balanced equation43: M1.1B – Use algebraic and geometric representations to describe and compare data by measuring and recording experimental data and use data in calculations such as calculating percent error48: 3.3c A balanced chemical equation represents conservation of atoms. The coefficients in a balanced chemical equation can be used to determine mole ratios in the reaction

1) How many moles of sodium atoms correspond to 1.56x1021 atoms of sodium?

2) How many moles of Al atoms are needed to combine with 1.58

mol of O atoms to make aluminum oxide, Al2O3?

3) How many moles of Al are in 2.16 mol of Al2O3?

4) Aluminum sulfate, Al2(SO4)3, is a compound used in sewage treatment plants.

a. Construct a pair of conversion factors that relate moles of aluminum to moles of sulfur for this compound

b. Construct a pair of conversion factors that relate moles of sulfur to moles of Al2(SO4)3

c. How many moles of Al are in a sample of this compound if the sample also contains 0.900 mol S?

d. How many moles of S are in 1.16 mol Al2(SO4)3?

5) How many moles of H2 and N2 can be formed by the decomposition of 0.145 mol of ammonia, NH3?

6) What is the total number of atoms in 0.260 mol of glucose,

C6H12O6?

7) What is the mass of 1.00 mol of each of the following elements?

a. Sodiumb. Sulfurc. Chlorine

8) Determine the mass in grams of each of the following:a. 1.35 mol Feb. 24.5 mol Oc. 0.876 mol Cad. 1.25 mol Ca3(PO4)2e. 0.625 mol Fe(NO3)3f. 0.600 mol C4H10g. 1.45 mol (NH4)2CO3

9) Calculate the number of moles of each compound:a. 21.5 g CaCO3b. 1.56 g NH3c. 16.8 g Sr(NO3)2d. 6.98 g Na2CrO4

Percent composition and empirical formulas

10) Calculate the percentage composition by mass of each element in the following compounds:

a. NaH2PO4b. NH4H2PO4c. (CH3)2CO

11) Phencyclidine is C17H25N. A sample suspected of being this illicit drug was found to have a percentage composition of 83.71% C, 10.42% H, and 5.61% N. Do these data acceptably match the theoretical data for phencyclidine?

12) How many grams of O are combined with 7.14x1021 atoms of N

in the compound N2O5?

13) Quantitative analysis of a sample of sodium pertechnetate with a mass of 0.896g found 0.111g Na and 0.477g technetium (Tc). The remainder was oxygen. Calculate the empirical formula of sodium pertechnetate, NaxTcyOz.

14) A substance was found to be composed of 22.9% Na, 21.5% B,

and 55.7% O. What is the empirical formula of this compound?

15) When 0.684 g of an organic compound containing only C, H, and O was burned in oxygen 1.312g CO2 and 0.805g H2O were obtained. What is the empirical formula of the compound?

Balancing equations

16) Write the equation that expresses in acceptable chemical

shorthand the following statement: “Iron can be made to react with molecular oxygen (O2) to give iron oxide with the formula Fe2O3”

17) Balance the following reactions:

a. Ca(OH)2 + HCl CaCl2 + H2Ob. AgNO3 + CaCl2 Ca(NO3)2 +AgClc. Fe2O3 + C Fe + CO3d. NaHCO3 + H2SO4 Na2SO4 + H2O + CO2e. C4H10 + O2 CO2 +H2Of. Mg(OH)2 + HBr MgBr2 + H2Og. Al2O3 + H2SO4 Al2(SO4)3 + H2Oh. KHCO3 + H3PO4 K2HPO4 + H2O + CO2i. C9H10O + O2 CO2 + H2O

Stoichiometry/limiting reactants

18) Chlorine is used by textile manufacturers to bleach cloth. Excess chlorine is destroyed by its reaction with sodium thiosulfate, Na2S2O3:

Na2S2O3(aq) + 4Cl2(g) + 5H2O(aq) 2NaHSO4(aq) + 8HCl(aq)a. How many moles of Na2S2O3 are needed to react with

0.12mol of Cl2?b. How many moles of HCl can form from 0.12mol of Cl2?c. How many moles of H2O are required for the reaction of

0.12mol of Cl2?d. How many moles of H2O react if 0.24mol HCl is formed?

19) The incandescent white of a fireworks display is caused by the reaction of phosphorous with O2 to give P4O10.

a. Write the balanced chemical equation for the reaction.b. How many grams of O2 are needed to combine with 6.85g

of P?c. How many grams of P4O10 can be made from 8.00g of O2?d. How many grams of P are needed to make 7.46g P4O10?

20) In dilute nitric acid, HNO3, copper metal dissolves according to the following equation:

3Cu(s) + 8HNO3(aq) 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(aq) How many grams of HNO3 are needed to dissolve 11.45g of Cu?

21) The reaction of powdered aluminum and iron(II)oxide,

2Al(s) + Fe2O3(s) Al2O3(s) + 2Fe(l)produces so much heat the iron that forms is molten. Because of this, railroads use the reaction to provide molten steel to weld steel rails together when laying track. Suppose that in one batch of reactants 4.20mol Al was mixed with 1.75mol Fe2O3.

a. Which reactant, if either, was the limiting reactant?b. Calculate the mass of iron (in grams) that can be formed

from this mixture of reactants.

22) Silver nitrate, AgNO3, reacts with iron(III) chloride, FeCl3, to give silver chloride, AgCl, and iron(III) nitrate, Fe(NO3)3. A solution containing 18.0g AgNO3 was mixed with a solution containing 32.4g FeCl3. How many grams of which reactant remains after the reaction is over?

Theoretical and percent yield

23) Barium sulfate, BaSO4, is made by the following reaction:

Ba(NO3)2(aq) + Na2SO4(aq) BaSO4(s) + 2NaNO3(aq)An experiment was begun with 75.00g of Ba(NO3)2 and an excess of Na2SO4. After collecting and drying the product, 63.45g BaSO4 was obtained. Calculate the theoretical yield and percent yield of BaSO4.

24) Aluminum sulfate can be made by the following reaction:2AlCl3(aq) + 3H2SO4(aq) Al2(SO4)3(aq) + 6HCl(aq)

It is quite soluble in water, so to isolate it the solution has to be evaporated to dryness. This drives off the volatile HCl, but the residual solid has to be treated to a little over 200C to drive off all the water. In one experiment, 25.0g of AlCl3 was mixed with 30.0g H2SO4. Eventually, 28.46g of pure Al2(SO4)3 was isolated. Calculate the percent yield.

Answers

1) 2.59x103mol Na atoms 2) 1.05mol Al 3) 4.32mol Al4) a. 2mol Al/3mol S b. 3mol S/1mol Al2(SO4)3 c.

0.600mol Al d. 3.48mol S5) 0.0725mol N2 and 0.218mol H26) 3.76x1024 atoms7) a. 23.0g Na b. 32.1g S c. 35.3g Cl8) a. 75.4g Fe b. 392g O c. 35.1g Ca d. 388g

Ca3(PO4)2

e. 151g Fe(NO3)2 f. 34.9g C4H10 g. 139g (NH4)2CO39) a. 0.215mol b. 0.0916mol c.

0.0794mol d. 4.31x108mol10) a. 19.2% Na, 1.68% H, 25.8% P, 53.3% O

b. 12.2% N, 5.26% H, 26.9% P, 55.6%O c. 62.0% C, 10.4% H, 27.6% O

11) Theoretical data (83.89% C, 10.35% H, 5.76% N) are consistent with experimental results.

12) 0.474g O13) NaTcO414) Na2B4O715) C2H6O16) 4Fe + 3O2 2Fe2O3 17)

a. Ca(OH)2 + 2HCl CaCl2 + 2H2Ob. 2AgNO3 + CaCl2 Ca(NO3)2 + 2AgClc. 2Fe2O3 + 3C 4Fe + 3CO3d. 2NaHCO3 + H2SO4 Na2SO4 + 2H2O + 2CO2e. 2C4H10 + 13O2 8CO2 + 10H2Of. Mg(OH)2 + 2HBr MgBr2 + 2H2Og. Al2O3 + 3H2SO4 Al2(SO4)3 + 3H2Oh. 2KHCO3 + H3PO4 K2HPO4 + 2H2O + 2CO2i. C9H10O + 14O2 9CO2 + 10H2O

18) a. 0.030mol Na2S2O3 b. 0.24mol HCl c. 0.15mol H2O d. 0.15mol H2O

19) a. 4P + 5O2 P4O10 b. 8.85g O2 c. 14.2g P4O10 d. 3.26g P

20) 30.31g HNO321) a. limiting reactant is Fe2O3 b. 195g Fe is formed22) 26.7g of FeCl3 are left over23) theoretical yield = 66.98g BaSO4, % yield = 94.73%24) % yield = 88.74%

Top of Form

1 . Which unit is most analogous to a mole?

a fluid ouncea dozena milea degree Fahrenheit

a pound

2 . In order to balance the equation C2H6 + O2 ---> H2O + CO2, you should

change the subscript of O in water to 2 to help balance the O.add O2 to the product side to help balance the O in the equation.change the coefficients.add H2 to the products to balance H.

3 . Balance the following equation:

B10H18 + O2 B2O3 + H2O

B10H18 + 7O2 5B2O3 + 9H2O

B10H18 + 9O2 5B2O3 + 9H2O

B10H18 + 19O2 10B2O3 + 9H2O

B10H18 + 12O2 5B2O3 + 9H2O

4 . Balance the following equation and indicate whether it is a combustion, combination, or decomposition reaction.

H2O2(l) H2O(l) + O2(g)

2H2O2(l) 2H2O(l) + O2(g), decomposition reaction

H2O2(l) H2O(l) + O2(g), decomposition reaction

H2O2(l) H2O(l) + (1/2)O2(g), decomposition reaction

H2O2(l) H2O(l) + (1/2)O2(g), combination reaction

H2O2(l) H2O(l) + O2(g), combustion reaction

5 . Convert the following description into a balanced equation:

When ammonia gas, NH3(g), is passed over hot sodium, hydrogen gas is released and sodium amide, NaNH2, is formed as a solid product.

Be sure to indicate the state of each element or compound.

2NH3 + Na 2NaNH2 + H2

NH3 + Na NaNH2 + H2

2NH3(g) + 2Na(s) 2NaNH2(s) + H2(g)

2NH3 + 2Na 2NaNH2 + H2

2NH3(g) + 2Na(s) 2NaNH2(s) + H2(l)

6 . How many molecules of CH2O are in 30.0 g of CH2O?

1.006.02 x 1023

1.81 x 1025

5.32 x 10-23

7 . Calculate the mass in mg of Na+ in 10.0 g of sodium carbonate.

4.34 x 103 mg46.0 mg2.77 mg4.34 mg0.23 mg

8 . How many carbon atoms are there in 200 molecules of C3H8O?

1.20 x 1026

2003.61 x 1026

600

9 . A sample of vitamin A, C20H30O, contains 4.0 x 1022 atoms of carbon. How many atoms of hydrogen and how many molecules of vitamin A does it contain?

6.0 x 1022 atoms of H, 8.0 x 1023 molecules of vitamin A4.0 x 1022 atoms of H, 4.0 x 1022 molecules of vitamin A6.0 x 1022 atoms of H, 4.0 x 1022 molecules of vitamin A6.0 x 1022 atoms of H, 2.0 x 1021 molecules of vitamin A

10 . The element zinc consists of five isotopes with masses 63.929, 65.926, 66.927, 67.925, and 69.925 amu. The relative abundances of these five isotopes are 48.89, 27.81, 4.110, 18.57, and 0.62 percent,

respectively. From these data calculate the average atomic mass of zinc.

66.93 amu65.39 amu66.927 amu65.389 amu63.93 amu

11 . What is the mass in grams of 0.257 mol of sucrose, C12H22O11?

12.5 g88.0 g7.51 x 10-4 g8.80 g342 g

12 . Determine the approximate formula weight of the following:

Ca(C2H3O2)2

691581529994

Problem Solving Center

Homework 2Top of Form

1 . What numbers would properly balance the reaction ___ C12H26 + ___ O2 ---> ___ CO2 + ___ H2O ?

1, 25, 12, 132, 37, 24, 262, 37, 24, 131, 38, 12, 26

2 . Complete the following statement: _____________ are in 10.0 moles of C10H8.

6.022 x 1024 atoms of C10.0 moles of C8.00 moles of H4.818 x 1024 atoms of H4.818 x 1025 atoms of H


Al + Cr2O3 Al2O3 + Cr

2Al + Cr2O3 Al2O3 + 2Cr

2Al + Cr2O3 Al2O3 + Cr

Al + Cr2O3 Al2O3 + 2Cr

4Al + 2Cr2O3 2Al2O3 + 4Cr


C6H14O + O2 CO2 + H2O

2C6H14O + 18O2 12CO2 + 14H2O

2C6H14O + 4O2 2CO2 + 2H2O

C6H14O + (19/2)O2 6CO2 + 7H2O

C6H14O + 9O2 6CO2 + 7H2O

2C6H14O + 19O2 12CO2 + 14H2O

5 . Balance the following equation and indicate whether it is a combustion, combination, or decomposition reaction.

H2O2 + SO2 H2SO4

H2O2 + SO2 H2SO4, decomposition reaction

2H2O2 + SO2 H2SO4, decomposition reaction

2H2O2 + SO2 H2SO4, combination reaction

H2O2 + SO2 H2SO4, combination reaction

6 . Calculate the number of molecules in 6.2 g of formaldehyde, CH2O.

3.7 x 1024

1.2 x 1023

6.0 x 1023

2.4 x 1023

7 . Calculate the mass in grams of 0.0112 mol of -fructose, C6H12O6.

180 g1.12 g2.02 g0.0112 g

8 . A sample of glucose, C6H12O6, contains 4.0 x 1022 atoms of carbon. How many atoms of hydrogen and how many molecules of glucose does it contain?

8.0 x 1022 atoms of H, 6.7 x 1021 molecules of glucose8.0 x 1022 atoms of H, 8.0 x 1022 molecules of glucose8.0 x 1022 atoms of H, 2.4 x 1023 molecules of glucose4.0 x 1022 atoms of H, 4.0 x 1022 molecules of glucose8.0 x 1022 atoms of H, 4.0 x 1022 molecules of glucose

9 . The element oxygen consists of three isotopes with masses 15.994915, 16.999133, and 17.99916. The relative abundances of these three isotopes are 99.7587, 0.0374, and 0.2039, respectively. From these data calculate the average atomic mass of oxygen.

15.993015.99937715.99491516.015.999415.9563

10 . Calculate the number of atoms in 48.0 g glucose, C6H12O6.

1.60 x 1023

9.24 x 1025

3.85 x 1024

2.89 x 1025

1.64 x 1016

11 . Calculate the molecular weight of xenon tetrafluoride, XeF4, a colorless, crystalline compound at room temperature.

601.2150.376169.3207.3

12 . How many iron ions (Fe3+) are present in 43.6 g FeCl3?

2.63 x 1025

4.86 x 1023

0.8073.721.62 x 1023



1 . Which of these samples contains the most atoms?

a gram of germaniuma gram of franciuma gram of americiuma gram of galliuma gram of europium

2 . What is the percent yield of CaO in the reaction CaCO3 ---> CaO + CO2 if 5.33 g of CaO are obtained when 10.0 g of CaCO3 are used?

5.60 percent64.7 percent53.3 percent5.33 percent95.2 percent

3 . Calculate the percentage of carbon present in cadaverine, C5H14N2, a compound present in rotting meat.

58.8 percent C68.2 percent C67.4 percent C

51.7 percent C

4 . What is the empirical formula of a compound that contains 7.989 g of carbon and 2.011 g of hydrogen?

C2H5

C8H2

CH3

C3HC2H6

5 . Give the empirical formula of the following compound if a sample contains 40.0 percent C, 6.7 percent H, and 53.3 percent O by mass.

C2H4O2

CH20C3H6O3

C6HO8

6 . Determine the empirical formula of a compound that contains 52.9 percent aluminum and 47.1 percent oxygen.

AlOAl2O3

Al4O6

Al0.53O0.47

Al3O2

7 . In making H2O from hydrogen and oxygen, if we start with 4.6 mol of hydrogen and 3.1 mol of oxygen, how many moles of water can be produced and what remains unreacted?

2.3 mol of water would be produced, with 0.8 mol of O2 remaining.4.6 mol of water would be produced, with 0.8 mol of O2 remaining.7.7 mol of water would be produced, with 0.0 mol of O2 remaining.4.6 mol of water would be produced, with 0.0 mol of O2 remaining.3.1 mol of water would be produced, with 1.5 mol of O2 remaining.

8 . Automotive airbags inflate when sodium azide, NaN3, rapidly decomposes to its component elements via the reaction

2NaN3 2Na + 3N2.

How many grams of sodium azide are required to form 5.00 g of nitrogen gas?

3.33 g11.61 g15.48 g7.74 g

9 . What is the molecular formula of the following compound?

empirical formula C2H3, molar mass 54 g/mol

C2H3

C6H9

C4H6

C8H12

10 .

Aluminum and bromine react vigorously according to the following equation:

2Al(s) + 3Br2(l) 2AlBr3(s)

What mass of product can be made by reacting 5.0 g of aluminum and 25 g of bromine?

11 g28 g62 g49 g42 g

11 .

The alcohol in "gasohol" burns according to the following equation:

C2H5OH + 3O2 2CO2 + 3H2O

How many grams of CO2 are produced when 3.00 g of C2H5OH are burned in this way?

5.74 g

88.0 g6.00 g2.87 g0.130 g

12 .

How many moles of H2O are produced when 2.5 mol of O2 react according to the following equation?

C3H8 + 5O2 3CO2 + 4H2O

3.02.54.02.0



1 . You are setting up a reaction between two chemicals that react according to the equation 3 A + 4 B ---> products. If you start with 1.00 mole each of both A and B, which chemical will be in excess at the end, and by how much (assuming the reaction goes to completion)?

Neither A nor B is in excess, because the reaction "goes to completion."B is in excess by 0.250 mol.B is in excess by 0.333 mol.A is in excess by 0.333 mol.A is in excess by 0.250 mol.

2 . What is the molecular formula of the following compound?

empirical formula CH, molar mass 78 g/mol

C4H4

C3H3

C6H6

CHC2H2

3 . Give the empirical formula of the following compound if a sample contains 57.8 percent C, 3.6 percent H, and 38.6 percent O by mass.

C4H3O2

C12H9O6

C2HOC8H6O4

4 . Based on the following structural formula, calculate the percentage of carbon present.

(CH2CO)2C6H3(COOH)

67.37 percent66.67 percent76.73 percent64.70 percent

5 . Calculate the mass percent of nitrogen in HNO3.

45.2 percent22.2 percent20.0 percent25.0 percentnone of these

6 . Which of the following cannot be an empirical formula?

C3H6

NO2

CHH2NCO2

7 . A manufacturer of bicycles has 5350 wheels, 3023 frames, and 2655 handlebars. How many bicycles can be manufactured using these parts?

2675 bicycles5350 bicycles3023 bicycles2655 bicycles

8 . CO2 exhaled by astronauts is removed from the spaceship atmosphere by reaction with KOH:

CO2 + 2KOH K2CO3 + H2O

How many kg of CO2 can be removed with 1.00 kg of KOH?

0.392 kg0.784 kg1.57 kg0.500 kg

9 . Aluminum and oxygen react according to the following equation:

4Al(s) + 3O2(g) 2Al2O3(s)

In a certain experiment 4.6 g Al was reacted with excess oxygen and 6.8 g of product was obtained. What was the percent yield of the reaction?

63 percent78 percent74 percent134 percent68 percent

10 .

For the reaction 3NO2 + H2O 2HNO3 + NO, how many grams of HNO3 can form when 1.00 g of NO2 and 2.25 g of H2O are allowed to react?

1.37 g0.913 g0.667 g

15.7 g

11 .

For the reaction Fe(CO)5 + 2PF3 + H2 Fe(CO)2(PF3)2(H)2 + 3CO, how many moles of CO are produced from a mixture of 5.0 mol Fe(CO)5, 8.0 mol PF3, and 6.0 mol H2?

18 mol5.0 mol6.0 mol12 mol15 mol

12 .

If 4.0 moles of Li and 2.0 moles of O2 are used in the reaction 4Li + O2 ---> 2Li2O, then the limiting reactant is _________ and the theoretical yield of Li2O is ____________ g.

oxygen, 6.0 x 10oxygen, 1.2 x 102

lithium, 3.0 x 10lithium, 6.0 x 10


Quiz 1Top of Form

1 . Write the balanced equation for the reaction that occurs when solid potassium nitrate is heated and decomposes to form solid potassium nitrite and oxygen gas.

2KNO3 2KNO2 + O2

2KNO4(s) 2KNO3(s) + O2(g)

2KNO3(s) 2KNO2(s) + O2(g)

KNO3(s) KNO2(s) + (1/2)O2(g)

2 . What is the formula weight of (NH4)2SO4? 118 amu100 amu116 amu132 amu

3 . Balance the following equation and indicate whether it is a combustion, combination, or decomposition reaction:

Li + N2 Li3N

Li + N2 3Li3N, decomposition reaction

6Li + N2 2Li3N, decomposition reaction

6Li + N2 2Li3N, combination reaction

Li + N2 3Li3N, combination reaction

6Li + N2 2Li3N, combustion reaction

4 . Suppose you are setting up a reaction that requires an iodide salt and are planning to use sodium iodide. However, at the last minute you find that you are out of sodium iodide, so you must use potassium iodide instead. Will you need to weigh out more, less, or the same mass of potassium iodide in order to get the same number of moles of iodide ions?

lesssamemore

5 . Convert the following to a balanced chemical reaction:

Gaseous hydrogen reacts with carbon monoxide to form methanol, CH3OH.

4H + CO CH3OH

H2 + CO CH3OH

2H2 + CO2 CH3OH

2H2 + CO CH3OH


Mg3N2 + H2O Mg(OH)2 + NH3

Mg3N2 + 6H2O 3Mg(OH)2 + NH3

Mg3N2 + 6H2O 3Mg(OH)2 + 2NH3

Mg3N2 + 2H2O Mg(OH)2 + NH3

Mg3N2 + 3H2O 3Mg(OH)2 + 2NH3

7 . Calculate the number of molecules in a tablespoon of table sugar, C12H22O11, weighing 10.5 g. 2.22 x 1023

3.01 x 1023

1.85 x 1022

6.32 x 1024

6.02 x 1023

8 . Potassium sulfate contains 44.9 percent potassium by mass. In a 50.0-g sample of potassium sulfate, the number of moles of potassium is 1.28 mol.2.00 mol.1.74 mol.0.287 mol.0.574 mol.

9 . The reaction C7H8 + 3HNO3 ---> C7H5N3O6 + 3H2O can be used to make TNT. How many grams of HNO3 are required to react with 10.0 g of C7H8? 20.5 g6.81 g30.0 g2.28 g10.1 g

10 .

Calculate the number of moles of water present in a 10.0-kg sample. 1.80 x 102 mol55.5 mol555 mol1.80 x 105 molnone of these

11 .

How many F- ions are present in 2.50 mol of BaF2? 5.003.01 x 1024

1.51 x 1024

2.508.31 x 10-24

12 .

What mass of silver chloride can be made from the reaction of 4.22 g of silver nitrate with 7.73 g of aluminum chloride? (Be sure to balance the reaction.)

AgNO3 + AlCl3 Al(NO3)3 + AgCl

24.9 g3.56 g10.7 g12.7 g

Practice QuestionsWrite the balanced equations for the following reactions.1. C2H6 + O2→ CO2 + H2O

2. Na + H2O → NaOH + H2

3. Ammonium nitrate decomposes to yield dinitrogen monoxide and water.

4. Ammonia reacts with oxygen gas to form nitrogen monoxide and water.

5. Iron (III) oxide reacts with carbon (C) to yield iron metal and carbon monoxide.

6. Hydrogen gas reacts with carbon monoxide to yield methanol (CH3OH). How many grams of methanol are formed when 15.6 g of hydrogen react with excess carbon monoxide?

7. How many moles of carbon dioxide are formed in the fermentation of 75 g of glucose?

8. The thermite reaction (Fe2O3 + Al → Fe + Al2O3) can be used to ignite solid-fuel rockets or bombs. How much aluminum is needed to react with 10.0 g of Fe2O3?

9. Identify the limiting reactant and how much ammonia gas can be produced when 7.2 g of nitrogen gas react with 1.5 g of hydrogen gas by the use of the Haber process: 3H2 + N2→ 2NH3.

10. Identify the limiting reactant and how much carbon dioxide gas can be produced when 15.2 g of methane react with 18.5 g of oxygen gas to produce water and carbon dioxide.

11. Identify the limiting reactant and how much nitric acid can be produced when 60.0 g of nitrogen dioxide react with 18.5 g of water to produce nitric acid and nitrogen monoxide.

12. Identify the limiting reactant and how much aspirin (C9H8O4) can be produced when 52.3 g of salicylic acid (C8H6O3) react with 25.0 g of acetic acid (CH3CO2H): C8H6O3 + CH3CO2H → C9H8O4 + H2O.

Calculate the percent yield for practice problems 9 through 12 if13. 6.3 g of ammonia were produced from problem 9.

14. 12.4 g of carbon dioxide were produced from problem 10.

15. 51 g of nitric acid were produced from problem 11.

16. 31.0 g of aspirin were produced from problem 12.

Answers1. 2C2H6 + 7O2 → 4CO2 + 6H2O

2. 2Na + 2H2O → 2NaOH + H2

3. NH4NO3 → N2O + 2H2O

4. 4NH3 + 5O2 → 4NO + 6H2O

5. Fe2O3 + 3C → 2Fe + 3CO

6. 124 g

7. 37 g

8. 3.38 g

9. Limiting reactant = H2; theoretical yield = 8.4 g

10. Limiting reactant = O2; theoretical yield = 12.7 g

11. Limiting reactant = NO2; theoretical yield = 55 g

12. Limiting reactant = salicylic acid; theoretical yield = 62.8 g

13. 75%

14. 97.6%

15. 93%

16. 56%

-

Match the Following

Chemistry: Chapter 9 Stoichiometry and Baking Soda (NaHCO3) as the Limiting Reactant Activity

Purposes: 1. Calculate theoretical mass of NaCl based on a known mass of NaHCO3.2. Experimentally determine the actual mass of NaCl produced.3. Calculate the percent yield for your experiment.

Reaction Equation: NaHCO3(s) + HCl(aq) NaCl(s) + CO2(g) + H2O(l)

Materials: safety glasses baking soda (NaHCO3) concentrated HCl and dropper

evaporating dish ring stand with ring bunsen burner and matches

watch glass wire gauze tongs

Procedure:

1. Find the mass of the evaporating dish and watch glass. Record this mass in the Data Table.2. Add 1/3 of a teaspoon of baking soda to the evaporating dish, and record the total mass in the

Data Table.3. Cover the evaporating dish with the watch glass so that only the spout of the evaporating dish

is exposed.4. Use the dropper to drip HCl down the spout and into the dish. Add HCl until the fizzing

ceases.5. Leaving the watch glass in place, boil off the liquid until only table salt (NaCl) remains in the

dish.6. Let the dish cool for five minutes, then weigh it again and record the mass in the Data Table.7. Clean up by rinsing your equipment with water and wiping dry with a paper towel.

Data Table: (please include units)

Quantity Measured Mass

evaporating dish, watch glass

evaporating dish, watch glass, NaHCO3

evaporating dish, watch glass, NaCl

Calculations:

1. Find the theoretical mass of NaCl that would be produced if your experiment were perfect.

2. Find the actual mass of NaCl that you obtained.

3. Find the percent yield for your experiment. If your percent yield is greater than 100%, provide at least one possible source of error that might have caused you to get more than 100% yield.

Chemistry: Ch.9 Complete Stoichiometry Review

1. How many moles of O2 should be supplied toburn 1 mol of C3H8 (propane) molecules in a camping stove?

2. How many moles of O2 molecules should besupplied to burn 1 mol of CH4 molecules in a domestic furnace?

3. Sodium thiosulfate (Na2S2O3), photographer’s“hypo” reacts with unexposed silver bromide in the film emulsion to form sodium bromide and a compound of formula Na5[Ag(S2O3) 3]. How many moles of Na2S2O3 formula units are needed to make 0.10 mol of AgBr soluble?

4. Calculate the mass of alumina (Al2O3)produced when 100 g of aluminum burns in oxygen.

5. “Slaked lime,” Ca(OH) 2, is formed from“quick-lime” (CaO) by adding water. What mass of water is needed to convert 10 kg of quicklime to slaked lime? What mass of slaked lime is produced?

6. Camels store the fat tristearin (C57H110O6) in the hump. As well as being a source of energy, the fat is a source of water, because when it is used the reaction

2 C57H110O6(s) + 163 O2(g) 114 CO2(g) + 110 H2O(l)

takes place. What mass of water is available from 1.0 kg of fat?

7. The compound diborane (B2H6) was at one time considered for use as a rocket fuel. How many grams of liquid oxygen would a rocket have to carry to burn 10 kg of diborane completely? (The products of the combustion are B2O3 and H2O.)

8. Given the balanced chemical equation

Br2 + 2 NaI 2 NaBr + I2

How many moles of sodium bromide (NaBr) could be produced from 0.172 mol of bromine (Br2)?

9. How many formula units of calcium oxide(CaO) can be produced from 4.9 x 105 molecules of oxygen gas (O2) that react with calcium (Ca) according to this balanced chemical equation?

2 Ca(s) + O2 (g) 2 CaO(s)

10. Aluminum metal (Al) reacts with sulfur (S) toproduce aluminum sulfide (Al2S3) according to this balanced chemical equation:

2 Al(s) + 3 S(s) Al2S3(s)

How many atoms of aluminum will react completely with 1.33 x 1024 atoms of sulfur?Name _____________________________ Hr ___

LIMITING REAGENTS

11. What is the maximum mass of methane (CH4) that can be burned if only 1.0 g of oxygen is available?

12. What is the maximum mass of glucose (C6H12O6) that can be burned in 10 g of oxygen?

13. The solid fuel in the booster stage of the space shuttle is a mixture of ammonium perchlorate and aluminum powder, which react as follows:

6 NH4ClO4(s) + 10 Al(s) 5 Al2O3(s) + 3 N2(g) + 6 HCl(g) + 9 H2O(g)

What mass of aluminum should be mixed with 5.0 x 103 kg of ammonium perchlorate, if the reaction proceeds as stated?

14. A solution containing 5.0 g of silver nitrate was mixed with another containing 5.0 g of potassium chloride. Which was the limiting reagent for the precipitation of silver chloride?

15. Given the balanced chemical equation

2 Ag + I2 2 AgI

How many atoms of silver metal (Ag) are required to react completely with 531.8 g of iodine (I2) to produce silver iodide (AgI)?

16. The theoretical yield of ammonia in an industrial synthesis was 550 tons, but only 480 tons was obtained. What was the percentage yield of the reaction?

17. Calculate the volume occupied by 16.3 moles ofnitrogen gas (N2) at STP.

18. How many moles of fluorine gas (F2) are contained in 0.269 dm3 container at STP?

19. Assuming that the gases are all at STP, find the volume of nitrogen dioxide gas (NO2) that could be produced from 71.11 dm3 of nitrogen gas (N2) according to this balanced chemical equation.

N2(g) + 2 O2(g) 2 NO2(g)

20. How many moles of oxygen (O2) would be needed to produce 79.60 moles of sulfur trioxide (SO3) according to the following balanced chemical equation?

2 SO2 + O2 2 SO3

21. How many grams of water will be produced from 50 g hydrogen reacting with 50 g oxygen?Think Critically

22. The reaction of 1 mol of C to form carbon monoxide in the reaction 2 C(s) + O2(g) 2 CO(g) releases 113 kJ of heat. How much heat will be released by the combustion of 100 g of C according the the above information?

23. According to the balanced chemical equation;how many atoms of silver will be produced from combining 100 g of copper with 200 g of silver nitrate?

Cu(s) + 2 AgNO3(aq) Cu(NO3) 2(aq) + 2 Ag(s)

24. According to the balanced chemical equation; how many moles of SO2(g) will be produced when 1.5 x 108 molecules of zinc sulfide react with 1000 dm3 of oxygen gas? Assume a 75% yield.

2 ZnS(s) + 3 O2 (g) 2 ZnO(s) + 2 SO2(g)

25. I need to produce 500 g of lithium oxide(Li2O)a) how many grams of Lithium ANDb) how many liters of oxygen do I need

The balanced equation is: Li + O2 LiO2

26. How many grams of water will be producefrom 50 g hydrogen reacting with 50 g oxygen?

Think Critically:





2 ZnS(s) + 3 O2 (g) 2 ZnO(s) + 2 SO2(g)

25. I need to produce 500 g of lithium oxide(Li2O)a. how many grams of Lithium ANDb. how many liters of oxygen do I need


26. How many grams of water will be produced from 50 g hydrogen reacting with 50 g oxygen?

Think Critically:





2 ZnS(s) + 3 O2 (g) 2 ZnO(s) + 2 SO2(g)




Think Critically:





2 ZnS(s) + 3 O2 (g) 2 ZnO(s) + 2 SO2(g)




Think Critically





2 ZnS(s) + 3 O2 (g) 2 ZnO(s) + 2 SO2(g)

25. I need to produce 500 g of lithium oxide(Li2O)a) how many grams of Lithium ANDb) how many liters of oxygen do I need


26. A tin ore contains 3.5% SnO2. How much tin is produced by reducing 2.0 kg of the ore with carbon?

SnO2 + C Sn + CO2

27. If 36.5 g of HCl and 73 g of Zn are put together:

2 HCl + Zn ZnCl2 + H2

a. Determine which reactant is the limiting reactant,b. Find the mass of ZnCl2 formed,c. Find the volume of H2 (@ STP) formed,d. Determine which reactant is in excess and by how much.

28. Many plants synthesize glucose by photosynthesis as follows: CO2(g) + H2O(l) + energy C6H12O6(s) + O2(g)

a. Write a balanced equation for this process,b. How many molecules of water are needed to make one molecule of glucose?c. How many liters of oxygen (@STP) are given off when 2.50 mol of glucose is

synthesized?d. How many moles of CO2 are needed for a plant to make 2.50 mole of glucose?e. How many carbon atoms are used to produce 2.50 mole of glucose?f. How many dm3 of oxygen gas are produced from 9.32 dm3 of CO2 (all @ STP)?

29. Assume that the human body requires daily energy that comes from metabolizing 816 g of sucrose, C12H22O11, using the following reaction:C12H22O11(s) + 12 O2(g) 12 CO2(g) + 11 H2O(l) + energy

How many dm3 of pure oxygen (@ STP) is consumed by a human being in 24 hours?

30. A student has a mixture of KClO3, K2CO3, and KCl. She heats 50 g of the mixture and determines that 5 g O2 and 7 g CO2 are produced by these reactions:

2 KClO3(s) 2 KCl(s) + 3 O2(g)K2CO3(s) K2O(s) + CO2(g)

KCl is not affected by the heat. What is the percent composition of the original mixture?

ANSWERS: 1. 5 mol O2

2. 2 mol O2

3. 0.3 mol Na2S2O3

4. 189 g Al2O3

5. 3214 g H2O and 13.2 kg slaked lime [Ca(OH) 2] 6. 998 g water 7. 34,783 g O2

8. 0.344 mol NaBr 9. 9.8 x 105 molecules CaO10. 8.9 x 1023 atoms Al11. 0.25 g CH4

12. 9.375 g C6H12O6

13. 1915 kg Al14. silver nitrate15. 2.5 x 1024 atoms Ag16. 87.3 % yield17. 365 L N2

18. 0.012 mol F2

19. 142 L NO2

20. 39.8 mol O2

21. 56.25 g H2O22. 942,000 J23. 7.1 x 1023 atoms Ag24. 1.9 x 10-16mol (NOT 2.5 x 10-16mol: 75% Yield)25a. g Li b. L O2

26. 27a. b. c. d. 28a. b. 6 c. 336 d. 15 e. 9 x 1024 f. 9.3229. 641 L O2

30. 15.2 g KCl

Name:________________________

Hour: ____ Date:___________

Chemistry: Percent Yield

Directions: Solve each of the following problems. Show your work, including proper units, to earn full credit.

1. “Slaked lime,” Ca(OH)2, is produced when water reacts with “quick lime,” CaO. If you start with 2 400 g of quick lime, add excess water, and produce 2 060 g of slaked lime, what is the percent yield of the reaction?

2. Some underwater welding is done via the thermite reaction, in which rust (Fe2O3) reacts with aluminum to produce iron and aluminum oxide (Al2O3). In one such reaction, 258 g of aluminum and excess rust produced 464 g of iron. What was the percent yield of the reaction?

3. Use the balanced equation to find out how many liters of sulfur dioxide are actually produced at STP if 1.5 x 1027 molecules of zinc sulfide are reacted with excess oxygen and the percent yield is 75%.

2 ZnS(s) + 3 O2(g) 2 ZnO(s) + 2 SO2(g)

4. The Haber process is the conversion of nitrogen and hydrogen at high pressure into ammonia, as follows:

N2(g) + 3 H2(g) 2 NH3(g)

If you must produce 700 g of ammonia, what mass of nitrogen should you use in the reaction, assuming that the percent yield of this reaction is 70%?

Answers: 1. 65% 2. 87% 3. 4.19 x 104 L SO2

4. 824 g N2

CHEMICAL REACTIONS OF COPPER AND PERCENT YIELD

Objective

To gain familiarity with basic laboratory procedures, some chemistry of a typical transition element, and the concept of percent yield.

Apparatus and Chemicals

0.5 g piece of no. 16 or no. 18 copper wire evaporating dish250 mL beaker (2) weighing paperconcentrated HNO3 (4 – 6 mL) 6.0 M H2SO4 (15 mL)graduated cylinder granular zinc3.0 M NaOH (30 mL) methanolcarborundum boiling chips acetonestirring rod toweliron ring and ring stand balancewire gauze aluminum foil cut in 1-inch squaresBunsen burner concentrated HCl (drops)

Discussion

Most chemical synthesis involves separation and purification of the desired product from unwanted side products. Some methods of separation, such as filtration, sedimentation, decantation, extraction, and sublimation were discussed earlier. This experiment is designed as a quantitative evaluation of your individual laboratory skills in carrying out some of these operations. At the same time you will become more acquainted with two fundamental types of chemical reactions -- redox reactions and metathesis (double-displacement) reactions. By means of these reactions, you will finally recover the copper sample with maximum efficiency. The chemical reactions involved are the following.

Cu(s) + 4 HNO3(aq) -----> Cu(NO3)2(aq) + 2 NO2(g) + 2 H2O(l) Redox [1]

Cu(NO3)2(aq) + 2 NaOH(aq) -----> Cu(OH)2(s) + 2 NaNO3(aq) Metathesis [2]

Cu(OH)2(s) -----> CuO(s) + H2O(g) Dehydration [3]

CuO(s) + H2SO4(aq) -----> CuSO4(aq) + H2O(l) Metathesis [4]

CuSO4(aq) + Zn(s) -----> ZnSO4(aq) + Cu(s) Redox [5]

Each of these reactions proceeds to completion. Metathesis reactions proceed to completion whenever one of the components is removed from the solution, such as in the formation of a gas or an insoluble precipitate (driving forces). This is the case for reaction [1], [2], and [3], where in reactions [1] and [3] a gas and in reaction [2] an insoluble precipitate are formed. Reaction [5] proceeds to completion because zinc has a lower ionization energy or oxidation potential that copper.

The objective in this experiment is to recover all of the copper you begin with, in analytically pure form. This is the test of your laboratory skills.

The percent yield of the copper can be expressed as the ratio of the recovered weight to initial weight, multiplied by 100:

% yield = x 100

Procedure

Weight approximately 0.500 g of no. 16 or no. 18 copper wire (1) to the nearest 0.0001 g

and place it in a 250 mL beaker. Add 4-5 mL of concentrated HNO3 to the beaker, IN

THE HOOD. After the reaction is complete, add 100 mL distilled H2O. Describe the

reaction (6) as to color change, evolution of gas, and change in temperature (exothermic

or endothermic) in the report sheet.

Add 30 mL of 3.0 M NaOH to the solution in your beaker and describe the reaction (7).

Add two or three boiling chips and carefully heat the solution -- while stirring with a glass

stirring rod -- just to the boiling point. Describe the reaction on your report sheet (8).

Remove the boiling chips.

Allow the black CuO to settle; then decant the supernantant liquid. Add about 200 mL of

very hot distilled water and allow the CuO to settle. Decant once more. What are you

removing by washing and decanting (9)?

Add 15 mL of 6.0 M H2SO4. What copper compound is present in the beaker now (10)?

Your teacher will tell you whether you should use Zn or Al for the reduction of Cu (II) in the following step.

A. ZincIn the hood, add 2.0 g of 30-mesh zinc metal all at once and stir until the supernatant liquid is colorless. Describe the reaction on your report sheet (11). What is present in solution (12)? When gas evolution has become very slow, heat the solution gently (but do not boil) and allow it to cool. What gas is formed in this reaction (13)? How do you know (14)?

B. AluminumIn the hood, add several 1-inch squares of aluminum foil and a few drops of concentrated HCl. Continue to add pieces of aluminum until the supernatant liquid is colorless. Describe the

recovered wt of Cu

initial wt of Co

reaction on your report sheet (11). What is present in solution (12)? What gas is formed in this reaction (13)? How do you know (14)?

When gas evolution has ceased, decant the solution and transfer the precipitate to a preweighed porcelain evaporating dish (3). Wash the precipitated copper with about 5 mL of distilled water, allow it to settle, decant the solution, and repeat the process. What are you removing by washing (15)? Wash the precipitate with about 5 mL of methanol (KEEP THE METHANOL AWAY FROM FLAMES _ IT IS FLAMMABLE!) Allow the precipitate to settle, and decant the methanol. (METHANOL IS ALSO EXTREMELY TOXIC: AVOID BREATHING THE VAPORS AS MUCH AS POSSIBLE.) Finally, wash the precipitate with about 5 mL of acetone (KEEP THE ACETONE AWAY FROM FLAMES - IT IS EXTREMELY FLAMMABLE!), allow the precipitate to settle, and decant the acetone from the precipitate. Prepare a steam bath as illustrated and dry the product on your steam bath for at least 5 minutes.

Wipe the bottom of the evaporating dish with a towel, remove the boiling chips and weigh the evaporating dish plus copper (2). Calculate the final a\weight of copper (4). Compare the weight with your initial weight and calculate the percent yield (5). What color is your copper sample (16)? Is it uniform in appearance (17)? Suggest possible sources of error in this experiment (18).

Chemical Reactions of Copper and Percent Yield Pre-lab (Review Questions)

1. Give an example, other than the ones listed in this experiment, of redox and metathesis

reactions.

2. When will reactions proceed to completion?

3. Define percent yield in general terms.

4. Name six methods of separating materials.

5. Give criteria in terms of temperature changes for exothermic and endothermic reactions.

6. If 1.65 g of Cu(NO3)2 are obtained from allowing 0.93 g of Cu to react with excess HNO3, what is the percent yield of the reaction?

Prelab – Chemical Reactions of Copper and Percent Yield

7. What is the maximum percent yield in any reaction?

8. What is meant by the terms decantation and filtration?

9. When Cu(OH)2(s) is heated, Copper (II) oxide and water are formed.

Write a balanced equation for the reaction.

10. When sulfuric acid and copper (II) oxide are allowed to react, copper (II) sulfate and water

are formed.

Write a balanced equation for this reaction.

11. When copper (II) sulfate and aluminum are allowed to react, aluminum sulfate and copper

are formed.

What kind of reaction is this? Write a balanced equation for this reaction.

REPORT SHEET

Chemical Reactions of Copper and Percent Yield

1. Weight copper initial _______________

2. Weight of copper and evaporating dish _______________

3. Weight of evaporating dish _______________

4. Weight of copper final _______________

5. % Yield (show calculations) _______________ 6. Describe the reaction Cu(s) + HNO3(aq) --> 7. Describe the reaction Cu(NO3)2(aq) + NaOH(aq) --> 8. Describe the reaction Cu(OH)2(s) -->

9. What are you removing by this washing (be specific)?

10. What copper compound is present in the beaker?

11. Describe the reaction CuSO4(aq) + Zn(s), or CuSO4(aq) + Al(s)

12. What is present in solution (aqueous)?

REPORT SHEET – page 2

Chemical Reactions of Copper and Percent Yield

13. What is the gas? Hint: Where did the HCl(aq) go? Why did you have to do this reaction in the fume hood?

14. How do you know?

15. What are you removing by washing?

16. What color is your copper sample?

17. Is it uniform in appearance?

18. Suggest possible sources of error in this experiment.

POST LAB QUESTIONS 1. If your percent yield of copper was greater than 100%, what are two plausible errors you may have made?

2. Consider the combustion of methane, CH4:CH4(g) + 2 O2(g) -----> CO2(g) + 2 H2O(g)

Suppose 2 mole of methane is allowed to react with 3 mol of oxygen.

a) What is the limiting reagent? (show work)

b) How many moles of CO2 can be made from this mixture? How many grams of CO2?

3. Suppose 8.00 g of CH4 is allowed to burn in the presence of 6.00 g of oxygen.

How much (in grams) CH4, O2, CO2, and H2O remain after the reaction is complete?

4. How many milliliters of 6.0 M H2SO4 are required to react with 0.80 g of CuO according to Equation [4]?

5. If 2.00 g of Zn is allowed to react with 1.75 g of CuSO4 according to Equation [5], how many grams of Zn will

remain after the reaction is complete?

6. What is meant by the term limiting reagent? Explain

Show your work for all calculations.

1. What volume of carbon dioxide can be produced by reacting 10.5 g baking soda (NaHCO3) with excess hydrochloric acid at STP according to the reaction below?

NaHCO3(s) + HCl(aq) → NaCl(aq) + CO2(g) + H2O(l)

2. Potassium chlorate decomposes to produce oxygen gas by the reaction shown below. What volume of oxygen gas can be produced by heating 5.89 g KClO3 at a pressure of 0.50 atmospheres and a temperature of 79 °C?

2 KClO3(s) → 2KCl(s) + 3O2(g)

3. Cetyl alcohol (C16H34O) is a flammable solid at room temperature. If 15.8 g of the alcohol are combusted, what volume of water vapor will be produced at a pressure of 1.26 atmospheres and a temperature of 110 °C? (Watch out — this equation isn't balanced!)

C16H34O(s) + O2(g) → CO2(g) + H2O(g)

Conclusion

Now, address the Focus Question: How much metal does it take to float a blimp? Given the information below, you should be able to calculate an answer.

Zinc reacts with sulfuric acid by the reaction shown below. If 759 kg zinc were to react with excess sulfuric acid, how large would a blimp be if it were filled with the hydrogen gas produced from this reaction at a pressure of 1.10 atm and a temperature of 22 °C?

Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)

Table 2Compound Formula Mass (amu)

MgO K2S

C3H8O3 Ca(NO3)2 Mg3(PO4)2

C6H2CH3(NO2)3 Pt(NH3)2Cl2 Fe(ClO4)2

Na2CO3 • 10H2O MgSO4 • 7H2O

Conclusion

Now address the Focus Question: Which has more mass—salt (NaCl) or sugar (C12H22O11)? Show calculations to support your answer.

A comparison of two domestic fuels - pollution

This sheet compares the amount of pollution produced by two domestic fuels - anthracite, thepurest form of coal, and propane, sold in cylinders as liquefied petroleum gas, LPG.Both anthracite and propane produce carbon dioxide when they burn.

1. What environmental problem does carbon dioxide contribute to?

..........................................................................................................................................

2. Give two practical consequences of this problem.

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Anthracite contains between 89% and 98% pure carbon. When carbon burns, carbon dioxide isformed and heat energy is produced.

C(s) + O2(g) ’ CO2(g) DH = -394 kJ mol-1

3. Calculate the mass of 1 mole of carbon dioxide. (RAMs: C = 12; O = 16)

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4. Calculate the mass of carbon dioxide formed per kJ of heat energy produced.

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Propane burns according to the equation:

C3H8(g) + 5O2(g) ’ 3CO2(g) + 4H2O(l) DH = -2220 kJ mol-1

5. Calculate the mass of carbon dioxide formed per kJ of heat energy produced when propaneburns.

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6. Which is the more environmentally friendly fuel in terms of carbon dioxide emission?

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Sulphur dioxide productionSulphur dioxide is formed when sulphur and sulphur-containing compounds burn.

7. What environmental problem does sulphur dioxide contribute to?

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8. Give two practical consequences of this problem.

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Coal often contains sulphur compounds, and these are converted into sulphur dioxide when thecoal burns. At the moment there is no way of removing sulphur dioxide from the gasesproduced by homes. Propane is freed of sulphur-containing compounds at the refinery. The sulphur compounds are converted into sulphur dioxide which can then be used to manufacture a useful chemical.

9. Which chemical?

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10. Which is the more environmentally friendly fuel in terms of sulphur dioxide emission?

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1. Copper reacts with nitric acid according to the following reaction:3 Cu (s) + 8 HNO3 (aq) 3 Cu(NO3)2 (aq) + 2 NO (g) + 4 H2O (l)

If an pre 1982 copper penny contains 3.10 grams of copper, what volume of 8.00 M nitric acid is required to exactly consume it? What volume of nitrogen monoxide gas

measured at STP would be produced? (Remember that 1 mole of any gas measured at STP = 22.4 dm3)

2. Hydrogen peroxide decomposes slowly to produce oxygen gas and water. Write a balanced equation for the decomposition of hydrogen peroxide. What mass of hydrogen peroxide (H2O2) must decompose to produce 0.77g of water?

3. Carbon monoxide is an air pollutant found in automobile exhausts. It slowly reacts with oxygen in the atmosphere to produce carbon dioxide. Write a balanced equation for this process. What mass of carbon dioxide would be produced from 10.00 grams of carbon monoxide? What mass of oxygen is required to convert the carbon monoxide to carbon dioxide?

4. Suppose that 50.0 cm3 of 2.00 M hydrochloric acid are added to 4.00 grams of zinc metal.

What it the limiting reagent? How many grams of zinc are actually consumed? What is the concentration of the hydrochloric acid solution after the reaction has occurred? What mass of hydrogen will be produced? Zn (s) + 2 HCl (aq) ZnCl2 (aq) + H2 (g)

5. Consider the reaction: 2 VO + 3 Fe2O3 6 FeO + V2O5

If 609.5 grams of vanadium (II) oxide, VO, and 832 grams of iron(III) oxide, Fe2O3, are put into a container and allowed to react according to the equation above, which substance(s) and how many grams of each would be present in the container after the reaction is complete?

6. Methyl alcohol (wood alcohol), CH3OH, is produced via the reactionCO(g) + 2 H2(g) CH3OH(l)

A mixture of 1.20 g H2(g) and 7.45 g CO(g) are allowed to react.(a) Which reagent is the limiting reagent?(b) What is the yield of CH3OH? [Assume theoretical yield in g is what is wanted here.](c) How much of the reagent present in excess is left over?(d) Suppose the actual yield is 7.52 g of CH3OH. What is the % yield?

7. A 0.32570 gram sample of NaClO3 is decomposed to form oxygen gas according to the following reaction:

2 NaClO3 (s) 2 NaCl (s) + 3 O2 (g)

The gas is collected over water at a total pressure of 742 torr at 23.0 oC. What volume of oxygen will be collected? (The vapor pressure of water at 23.0 oC is 20.65 torr)

8. Hydrogen is produced when zinc reacts with sulfuric acid according to the following reaction

Zn (s) + H2SO4 (aq) ZnSO4 (aq) + H2 (g)

If 159 cm3 of wet hydrogen is collected over water at 23.0o C and a total pressure of 738 torr, how many grams of zinc are consumed? (The vapor pressure of water at 23.0 oC is 20.65 torr)

Stoichiometry Challenge

1. (pg 129, #118) Nitric acid is produced commercially by the Ostwald process, represented by the following equations:

a. 4HN3(g) +5O2(g) 4NO(g) + 6H2O(g)b. 2NO(g) + O2(g) 2NO2(g)c. 3NO2(g) + H2O(l) 2HNO3(aq) + NO(g)

What mass of NH3 must be used to produce 1.o x 106 kg HNO3 by the Ostwald process? Assume 100% yield in each reaction and assume that the NO produced in the third step is not recycled.

2. (pg 129, #120) The aspirin substitute, acetaminophen (C8H9O2N), is produced by the following three-step synthesis:

a. C6H5O3N(s) + 3H2(g) + HCl(aq) C6H8ONCl(s) + 2H2O(l)b. C6H8ONCl(s) + NaOH(aq) C6H7ON(s) + H2O(l) + NaCl(aq)c. C6H7ON(s) + C4H6O3(l) C8H9O2N(s) + HC2H3O2(l)

The first two reactions have percent yields of 87% and 98% by mass, respectively. The overall reaction yields 3 mol of acetaminophen product for every 4 mol CH5O3N reacted.

a. What is the percent yield by mass for the overall process?b. What is the percent yield by mass of step III?

chemistry review - tfalachemistry - home · web viewi need to produce 500 g of lithium oxide(li2o)...

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