Chemistry 1 Chapter 9
Reaction Stoichiometry
Reaction stoichiometry is the mass relationships between reactants and products in a
balanced chemical reaction.
This obeys the law of conservation of mass.
Example: 2NaClO3  2NaCl + 3 O2
2(106.5 g)
2 (58.5 g) + 3 (32.0 g)
213.0 g = 213.0 g
What if you only had 1 mole of NaClO3, how many moles of NaCl and O2 will form?
Using the mole ratio from the balanced equation, 2 moles NaClO3 produces 2 moles of
NaCl and 3 moles of O2
Because 2 moles NaClO3 produces 2 moles of NaCl , the 1 mole will produce 1 mole of
NaCl .
Because 2 moles NaClO3 produces 3 moles of O2 , then 1.5 moles of O2 will form.
If different amounts of reactant or product are given, a math format is set up to solve for
any reactant or product.
Example: 24.3 g of sodium chlorate is heated and decomposed. How many grams of
oxygen are released.
given
2NaClO3  2NaCl + 3 O2
unknown
To solve, use the following conversions
Given grams x (1mole of given/mole mass of given) x ( moles unknown/ moles given) x(
mole mass of unknown/ 1 mole of unknown)
The mole ratio is from the balanced chemical reaction.
24.3 g NaClO3 x (1 mole NaClO3/106.5 g NaClO3 ) x (3 mole O2/ 2 Mole NaClO3) x
( 32.0 g of O2 / 1 mole of O2)
Lab mole ratio
= 11.0 g of O2
Worksheet SR 9.1