Stoichiometry
Calculating quantities in chemical
reactions.
Stoichiometry
1 frame and 3 wheels are needed to create one tricycle
If I use 1 dozen frames , how many tricycles can I make?
1 dozen
If I use 1 dozen wheels, how many tricycles can I make? 4 or (1/3 dozen)
Stoichiometry
2AgNO3 + H2S
Ag2S + 2HNO3
2 moles of silver nitrate yields 1 mole of
silver sulfide
Conversion Factor:
2 mole AgNO3 = 1 mole Ag2S
And 1 mole H2S yields 2 moles HNO3
2AgNO3 + H2S
3.5 mol
Ag2S + 2HNO3
? moles
How many moles of Ag2S will be produced
from 3.5 moles of AgNO3 ?
3.5 mole AgNO3 x 1 mole Ag2S = 1.75 mole Ag2S
2 mole AgNO3
How many grams of Ag2S will be produced from 3.5
moles of AgNO3?
1.75 mole Ag2S x 247.8g = 433.65g Ag2S
1 mole
Tell-tale sign of stoichiometry
Given information about one substance, and
being asked about a different substance.
Stoichiometry

A balanced chemical equation tells the
mole/mole ratio between different
compounds in the equation.
grams
mole X gmole Y
grams
Practice problem
What mass of Mg(OH)2 will react with 1.20g of HCl?
Mg(OH)2 + 2HCl g MgCl2 + 2H2O
1.20g HCl x 1 mol HCl = .0329mol HCl
36.5g
.0329mol HCl x 1 mol Mg(OH)2 = .0164 mol Mg(OH)2
2 mol HCl
.0164 mol Mg(OH)2 x 58.3g = .956 g Mg(OH)2
1 mol