1. Generic Stoichiometry
Z (aq) Y (aq)  M (s) T2 (g)
Given the following information:
Z = 20 g/mol
Y = 10 g/mol
M = 6 g/mol
T = 5 g/mol
If you combine 100 g of solution Z with 1.8 x 1024 molecules of solution Y:
How many moles of M will precipitate out of the solution?
What volume of T2 gas will be produced at STP?

2. Z (aq) + 2 Y (aq)  5 M (s) + T 2(g)
EXCESS
LIMITING
Z (aq) Y (aq)  M (s) T 2(g)
100 g x 1024 molecules
x mol
7.5 mol M
33.6 L T2
/ 20 g /mol
/ 6.02 x 1023 molecules/mol 2
3 mol Y 5
x mol M =
x 22.4L/mol
15 = 2x
2 : 5
3 mol Y
Easy
HAVE
5 mol Z
x = 7.5 mol 1 2
2 : 1
1.5 mol T2
NEED
1.5 mol Z
5 mol
10 mol Y
1.5 mol
SMALLER Number is LIMITING Reactant
EXCESS
LIMITING
1 mol Y
5 mol M
x mol M = 1.8 x 1024 molecules Y
= 7.5 mol M
6.02 x 1023 molecules Y
2 mol Y
1 mol T2
22.4 L T2
x L T2 = 3 mol Y
= L T2
2 mol Y
1 mol T2

3. Z (aq) + 2 Y (aq)  5 M (s) + T 2(g)
1.8 x 1024 molecules
x mol
3 mol Y
5 mol M
x mol M = 3 mol Y
= 7.5 mol M
2 mol Y Y M