Hon C9 2EF.notebook
January 25, 2016
Molar Volume at STP
one mole of gas has a volume of 22.4 L at STP (standard temperature and pressure).
Gas Stoichiometry: Practice!
A. What is the volume at STP of 4.00 g of CH4?
B. How many grams of He are present in 8.0 L of gas at STP? Hon C9 2EF.notebook
January 25, 2016
Gases and Stoichiometry
2 H2O2 ﴾l﴿ → 2 H2O ﴾g﴿ + O2 ﴾g﴿
Decompose 1.1 g of H2O2 in a flask with a volume of 2.50 L. What is the volume of O2 at STP? How many L of water vapor can be produced from the combustion of 1.06 gram of glucose (C6H12O6) @STP?
C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 6 H2O(g)
Hon C9 2EF.notebook
January 25, 2016
L of B
L of A
mol A
g of A
mol B
g of B
particles of A
particles of B
Mixed Stoichiometry Calculations
representative 1 mol G x
=
particles of G
6.02 x 1023
mass 1 mol G of G x mass G =
mol G x
volume of 1 mol G x
22.4 L G =
G at STP
x
6.02 x 1023 representative =
particles of W
1 mol W
b mol W = mol W
a mol G
x
x
mass W mass =
1 mol W
of W 22.4 L W Volume of =
1 mol W
W at STP
Hon C9 2EF.notebook
January 25, 2016
Limiting Reactant
Most of the time in chemistry we have more of one reactant than we need to completely use up other reactant.
Limiting Reactant ­ Reactant that is consumed first, limiting the amounts of products formed. Once it is consumed, the reaction stops.
LR animation
excess reactant ­there is too much, will be left over
Limiting Reactant
Try all of the reactants. Calculate how much of a product we can get from each of the reactants to determine which reactant is the limiting one.
The reactant that makes the least amount of product is the limiting reactant. Once you determine the limiting reactant, you should ALWAYS start with it!
Be sure to pick a product! You can’t compare to see which is greater and which is lower unless the product is the same!
Hon C9 2EF.notebook
January 25, 2016
Limiting Reactant: Example
0.050 g of aluminum reacts with 1.00 g of copper chloride to produce aluminum chloride. Which reactant is limiting, which is in excess, and how much aluminum chloride is produced?
2Al + 3CuCl2 → 2AlCl3 + 3Cu
Start with Al: