EQUATIONSEQUATIONS

Coefficients-Coefficients-

1. The big numbers in front of the 1. The big numbers in front of the compounds and/or elements in a compounds and/or elements in a chemical reactionchemical reaction..

2. Represent the 2. Represent the number of molesnumber of moles of that of that compound or element in a chemical compound or element in a chemical reactionreaction

3. Example:3. Example:

2H2H22 + O + O22 2H 2H22OO

All represent coefficients. This reads 2 moles All represent coefficients. This reads 2 moles of Hof H22 reacts with 1 mole of O reacts with 1 mole of O2 2 forms 2 forms 2

moles of Hmoles of H22OO

Subscripts-Subscripts-

1. Small numbers inside a chemical 1. Small numbers inside a chemical formulaformula

2. Represent the relative number of atoms in 2. Represent the relative number of atoms in a compounda compound

3. Example:3. Example:

Mg(NOMg(NO33))22

All represent subcripts. This means that this All represent subcripts. This means that this compound is made of 1 Mg and 2(NOcompound is made of 1 Mg and 2(NO33). ).

Each NOEach NO33 is made up of 1 N and 3 O is made up of 1 N and 3 O

SymbolsSymbols + means + means reacts with whenreacts with when on the on the

reactant side and means and on the reactant side and means and on the product sideproduct side

means means yields or producesyields or produces Δ means Δ means heat is appliedheat is applied

TYPES OF CHEMICAL REACTIONSTYPES OF CHEMICAL REACTIONS

Five Types of Chemical ReactionsFive Types of Chemical Reactions

1. Synthesis or direct combination1. Synthesis or direct combination

2. Decompostion or analysis2. Decompostion or analysis

3. Single replacement3. Single replacement

4. Double replacement4. Double replacement

5. Combustion5. Combustion

SYNTHESIS OR DIRECT SYNTHESIS OR DIRECT COMBINATIONCOMBINATION

Definition- Definition- AA reaction in which two or reaction in which two or more substance form a compoundmore substance form a compound

Identification –Look at the product side Identification –Look at the product side (right side(right side) ) there will be there will be only one productonly one product

HH22 O O22 B B22 I I22 N N22 Cl Cl22 , all are elements. , all are elements.

Examples: Examples: 2H2H22 + O + O22 2H 2H22OO

4Al + 3O4Al + 3O22 2Al 2Al22OO33

Ca + ClCa + Cl22 CaCl CaCl22

DECOMPOSITION OR DECOMPOSITION OR ANALYSISANALYSIS

Definition- Definition- A reaction in which a A reaction in which a compound is broken down.compound is broken down.

Identification- Look at the reactants (left Identification- Look at the reactants (left side) there will be side) there will be one compound.one compound.

Examples:Examples: 2HgO 2HgO 2Hg + O 2Hg + O22

2H2H22O O 2H 2H22 + O + O22

2KClO2KClO33 2KCl + 3O 2KCl + 3O22

SINGLE REPLACEMENTSINGLE REPLACEMENT

Definition- Definition- A reaction in which one element A reaction in which one element reacts with one compound to form another reacts with one compound to form another element and another compoundelement and another compound

Identification- Look at the reactants (left side) Identification- Look at the reactants (left side) there will be one there will be one element and one element and one compound Remember the diatomics, Hcompound Remember the diatomics, H22 O O22

BB22 I I22 N N22 Cl Cl22 , all are elements , all are elements

Examples:Examples: Zn + Cu(NOZn + Cu(NO33))22 Cu + Zn(NO Cu + Zn(NO33))22

Cu + 2 AgNOCu + 2 AgNO33 2Ag + Cu(NO 2Ag + Cu(NO33))22

Mg + 2HCl Mg + 2HCl H H22 + MgCl + MgCl22

DOUBLE REPLACEMENTDOUBLE REPLACEMENT

Definition- Definition- When two compounds react When two compounds react and form two other compoundsand form two other compounds

Identification- Look at the reactants (left Identification- Look at the reactants (left side) there will be side) there will be two compounds.two compounds.

Examples:Examples: NaOH + HCl NaOH + HCl NaCl + HOH NaCl + HOH AgNOAgNO33 + NaCl + NaCl AgCl + NaNO AgCl + NaNO33

3CaBr3CaBr22 + 2Na + 2Na33P P Ca Ca33PP22 + 6NaBr + 6NaBr

COMBUSTIONCOMBUSTION

Definition- Definition- A reaction in which an organic A reaction in which an organic compound is burned and the products compound is burned and the products are always carbon dioxide and waterare always carbon dioxide and water

Organic compound- a compound composed Organic compound- a compound composed of carbon and Hydrogenof carbon and Hydrogen

Identification- Look at the reactants and look Identification- Look at the reactants and look for Ofor O22 also the products will be CO also the products will be CO2 2 and H2O

Examples Examples CHCH44 + O + O22 CO CO22 + 2H + 2H22O O

CC33HH88 + 5O + 5O22 3CO 3CO22 + 4H + 4H22OO

BALANCING EQUATIONSBALANCING EQUATIONS

Equations are balanced to obey the Equations are balanced to obey the Law of Conservation of Mass.Law of Conservation of Mass.

To balance an equation coefficients are To balance an equation coefficients are added so that the number of atoms on added so that the number of atoms on each side is constanteach side is constant

YOU CAN NEVER CHANGE YOU CAN NEVER CHANGE SUBSCRIPTS TO BALANCE.SUBSCRIPTS TO BALANCE.

REACTION STOICHIOMETRY-REVISTEDREACTION STOICHIOMETRY-REVISTED

Steps for mole-mole problemsSteps for mole-mole problems

a. Copy the balanced equation(we will use a. Copy the balanced equation(we will use this as a “work area”this as a “work area”

b. Place the given number of moles above b. Place the given number of moles above that compound in the balanced equation.that compound in the balanced equation.

c. Place an X above the unknown substance c. Place an X above the unknown substance in the balanced equationin the balanced equation

d. Set up and solve a mole-coefficient ratiod. Set up and solve a mole-coefficient ratio

Example:Example: Hydrogen and oxygen react to produce Hydrogen and oxygen react to produce

water according to the following equation: water according to the following equation: 2H2H22 + O + O22 2H 2H22O. How many moles of O. How many moles of

oxygen gas needs to be reacted to produce oxygen gas needs to be reacted to produce 7.5 moles of water?7.5 moles of water? 2H2H22 + O + O22 2H 2H22OO

Answer:3.75 moles of OAnswer:3.75 moles of O22