The document discusses mole calculations including mole-mole, mole-mass, mass-mass, mole-molecule, and mass-molecule conversions. It also covers gas stoichiometry problems, determining empirical and molecular formulas, and calculations involving limiting reagents and percent yield. Sample problems are provided for each type of calculation to demonstrate how to determine the number of moles, grams, or molecules of reactants and products.

1. By Keonho Kim, Sanggu
Lee

2. What is mole?
The mole mass is depends on how many
electrons are in each atom.
For example; H has a mass of 1.01, O has
mass of 16. H has less electrons than what O
has, so the mass of the H is less than O, also
we could find that Mole mass is depends on
electron

3. What is atomic mass and molar mass?
Atomic mass - It is approximately equivalent to
the number of protons and neutrons in the
atom.
Molar mass - The molar mass is a physical
property. It is defined as the mass of a given
substance divided by its amount of
substance.

4. Conversions
Mole - Mole
Mole - Mass
Mass - Mass
Mole - Molecule
Mass - Molecule
Mixed: Mole - Mass - Molecule
Mole - volume
Mass - volume

5. Mole - Mole
2H2+O2 → 2H2O
How many moles of H2 are required to make 10 moles of water?
H2O
mole mass
1
H2
mole mass
16.04
1
1.01
10 160.4
x
10.1
x = 10

6. Mole - Mass
2H2+O2 → 2H2O
How many grams of water can be made with 8 moles of oxygen?
H2O
mole mass
O2
mole mass
1
16.04
1
6
8
x
8
48
To find x we need to do cross multiply.
x = 128.32

7. Mass - Mass
2H2+O2 → 2H2O
How many grams of water can be made with 76g of Oxygen?
H2O
O2
mole mass
1
16.04
8
x
x = 42
mole mass
1
6
12.6 76

8. Mole - Molecule
2H2+O2 → 2H2O
How many moles of H2O are formed from 8.038*1023 molecules of O2
O2
mole molecule
1 6.023x1023
8.038x1023
x=
H2O
mole molecule
2 6.023x1023
x

9. Mass - Molecule
2H2+O2 → 2H2O
How many Molecule of O2 when H2O has a mass of 57.5
O2
H2O
mole mass molecule mole mass molecule
1
32 1.20E24
1.90E24
2
36.4 1.20E24
57.5

10. Mixed :Mole - Mass - Molecule
2H2+O2 → 2H2O
How many mole and mass of O when a H2O has a molecule of 6.5 X 1023
O
H2O
mole mass molecule
mole mass molecule
32 6.023*1023
2 36.02 1.2*1023
1
5.4 173.3 3.26*1024
6.5*1023

11. Mole - Volume
How many moles of argon atoms are present in 11.2 L of argon gas at STP?
Answer
0.5 mole Because 1 mole of any gas is 22.4 at STP. So it is 0.5 mole.

12. Mass - Volume
How many mass of Hydrogen atoms are present in 50 L of gas at oxygen?
H
mass volume
1.01 11.2
x
Answer- 2.25
O2
mass volume
32
22.4
50

13. Gas Stoichiometry? Remember?
2Na(s) + 2H2O(I) → H2(g) + 2NaOH(aq)
How many grams of sodium metal are needed to give 7.81g of hydrogen by this reaction?
Na
mole mass
2
45.98
H
mole mass
1
x
x = 178g Na
2.02
7.81

14. Gas Stoichiometry? Remember?
2Na(s) + 2H2O(I) → H2(g) + 2NaOH(aq)
How many molecule sodium water are needed to react with 1.25*10 24 molecules of water?
Na
H2O
mole molecule mole molecule
2
1.20E24
x
2 1.2046E24
1.25E24
x = 1.25 x 10E24 atoms Na

15. Empirical and Molecular formula
A 20g sample of a hydrate of nickel sulfate (NiSO4) lost 9.63g of water when heated. Determine the
hydrate’s formula.

16. Percent yield and Limiting reagent
Methane, CH4, burns in oxygen to give carbon dioxide and water according to
the following equation:
CH4 + 2 O2 ------> CO2 + 2 H2O
a mixture of 0.350mol of methane was burned in 3mol of oxygen in a sealed
steel vessel. Find the limiting reactant, if any, and calculate the theoretical
yield, (in moles) of water.
1 mol CH4 = 2 mol O2
If we use up all the methane then:
1 mol CH4 = 2 mol O2
0.350 mol
x
x = 0.70 mol of O2 would be needed.

17. continue
If we use up all the oxygen then
1 mol CH4 = 2 mol O2
x
3 mol
x = 1.5 mol of methane.
We don't have 3 moles of methane. We have only 0.35 moles. Therefore the methane will be used
up before all the oxygen is. Again the methane is the limiting reactant.
We now use the limiting reactant to make the mole comparison across the bridge to find the amount
of water produced.
1 mol CH4 = 2 H2O
0.25 mol
x
x = 0.70 mol of H2O would be produced.
When 0.35 mole of methane and 3 mole of oxygen are mixed and reacted according to the
equation, the methane is the limiting reactant and the maximum yield of water will be 0.70 moles.