Chapter Three: Stoichiometry

Question 1

a chemical reaction in which two or more substances combine to form a single product

Answer 1

Combination Reaction

Question 2

What type of reaction is this
2Mg (s) + O2 (g) —> 2MgO (s)

Answer 2

combination reaction

Question 3

a single reactant breaks apart to form two or more substances. Many compounds react this way when heated

Answer 3

Decomposition reaction

Question 4

what type of reaction is this?
PbCO3 (s) —> PbO (s) + CO2 (g)

Answer 4

Decomposition Reaction

Question 5

a chemical reaction that proceeds with evolution of heat and usually also a flame; most of these reactions involve oxygen, as in the burning of a match

Answer 5

combustion reaction

Question 6

what type of reaction?
C3H8 (g) +5O2 (g) —> 3CO2 (g) + 4H2O (g)

Answer 6

Combustion reaction

Question 7

the sum of the atomic weights (AW) of the atoms in the chemical formula of the substance

Answer 7

Molecular Weight (MW) or Formula Weight (FW)

Question 8

the percentage composition of an element in a substance

Answer 8

elemental composition

Question 9

elemental composition equation

Answer 9

% mass composition of element = [(# of atoms of element) (atomic weight of element) / FW] x 100

Question 10

a collection of Avogadro’s number (6.022 x 10^23) of objects

Answer 10

Mole

Question 11

the mass of one mole of a substance in grams; it is numerically equal to the formula weight in atom mass units

Answer 11

Molar Mass

Question 12

the reactant that is completely consumed in a reaction; the amount of product that can form is limited by the complete consumption of this reactant

Answer 12

Limiting Reactant

Question 13

the quantity of product that is calculated to form when all of the limiting reagent reacts

Answer 13

Theoretical Yield

Question 14

the ratio of the actual (experimental) yield of a product to its theoretical (calculated) yield, multiplied by 100

Answer 14

percent yield

Question 15

Percent yield equation

Answer 15

percent yield = (actual yield / theoretical yield) x 100

Question 16

the study of the quantitative relationships between chemical formulas and chemical equations

Answer 16

Stoichiometry

Question 17

What are the three rules for balancing equations?

Answer 17

1. Never change chemical formula
2. Never add new reactants or products
3. Must balance with smallest coefficients possible

Question 18

What is Avogadro’s number? What does it represent?

Answer 18

6.022 x 10^23
the amount of substance that contains (avogadro’s number) units of that substance

Question 19

A combustion reaction is a rapid reaction that produces a flame. The reaction commonly occurs between a hydrocarbon and oxygen to produce what two things?

Answer 19

Carbon Dioxide and Water