chapter10 section03 percent composition and chemical formulas by hamdy karim

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chemistry

© Copyright Pearson Prentice Hall

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Percent Composition and Chemical Formulas

It helps to know the percents of the components in a shirt because they affect how warm it is, whether it will need to be ironed, and how it should be cleaned. You will learn how the percents of the elements in a compound are important in chemistry.

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The Percent Composition of a Compound

The Percent Composition of a Compound

How do you calculate the percent by mass of an element in a compound?

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> The Percent Composition of a Compound

The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100%.

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Percent Composition from Mass Data

The relative amounts of the elements in a compound are expressed as the percent composition or the percent by mass of each element in the compound.

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SAMPLE PROBLEM

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SAMPLE PROBLEM

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SAMPLE PROBLEM

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SAMPLE PROBLEM

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Practice Problems for Sample Problem 10.9

Problem Solving 10.33 Solve Problem 33 with the help of an interactive guided tutorial.

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Percent Composition from the Chemical Formula

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SAMPLE PROBLEM

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Problem Solving 10.34 Solve Problem 34 with the help of an interactive guided tutorial.

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Percent Composition as a Conversion Factor

You can use percent composition to calculate the number of grams of any element in a specific mass of a compound.

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Propane (C3H8) is 81.8% carbon and 18% hydrogen. You can calculate the mass of carbon and the mass of hydrogen in an 82.0 g sample of C3H8.

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Empirical Formulas

Empirical Formulas

What does the empirical formula of a compound show?

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> Empirical Formulas

The empirical formula gives the lowest whole-number ratio of the atoms of the elements in a compound.

The empirical formula of a compound shows the smallest whole-number ratio of the atoms in the compound.

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> Empirical Formulas

Ethyne (C2H2) is a gas used in welder’s torches. Styrene (C8H8) is used in making polystyrene.

These two compounds of carbon have the same empirical formula (CH) but different molecular formulas.

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SAMPLE PROBLEM

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Problem-Solving 10.37 Solve Problem 37 with the help of an interactive guided tutorial.



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Molecular Formulas

Molecular Formulas

How does the molecular formula of a compound compare with the empirical formula?

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> Molecular Formulas

The molecular formula of a compound is either the same as its experimentally determined empirical formula, or it is a simple whole-number multiple of its empirical formula.

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> Molecular Formulas10.3

Methanal, ethanoic acid, and glucose all have the same empirical formula—CH2O.

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> Molecular Formulas10.3


SAMPLE PROBLEM

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Problem-Solving 10.38 Solve Problem 38 with the help of an interactive guided tutorial.


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Section Quiz

-or-Continue to: Launch:

Assess students’ understanding of the concepts in Section

10.3 Section Quiz.

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1. Calculate the percent by mass of carbon in cadaverine, C5H14N2, a compound present in rotting meat.

a. 67.4% C

b. 58.8% C

c. 51.7% C

d. 68.2% C

10.3 Section Quiz.


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2. Which of the following is NOT an empirical formula?

a. NO2

b. H2N

c. CH

d. C3H6

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10.3 Section Quiz.

3. Determine the molecular formula of a compound that contains 40.0 percent C, 6.71 percent H, and 53.29 percent O and has a molar mass of 60.05 g.

a. C2H4O2

b. CH2O

c. C2H3O

d. C2H4O


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> Concept Map 10

Concept Map 10 Solve the Concept Map with the help of an interactive tutorial.

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chapter10 section03 percent composition and chemical formulas by hamdy karim

Education

compound percent composition

different molecular

empirical formula ch2o

compound propane c3h8

g sample of c3h8

mass of carbon

mass of hydrogen

mass data