Mole Calculations PracticeExam
Name:
Period:
Short Answer
1. Relate the terms mole, atoms, and Avogadro.
Avogadro’s number is the number of atoms in a mole
2. Discuss how Oxygen can have both a molecular and atomic mass.
Oxygen is diatomic, so you can have an atom of oxygen or a molecule of the
element.
3. How can a chemist know an atom ratio without being able to see atoms?
Moles baby!
4. Define atomic weight.
The number of grams in a mole of the atom.
5. Discuss how a mole of Carbon can have different mass than a mole of Lead.
A mole of carbon has a different mass than a mole of lead because each atom of
carbon has a different mass than lead.
6. Discuss two ways to measure out a mole of molecules.
You can measure out grams of a solid, mL of a liquid or solution, Liters of a
gas…there are many ways to measure a mole.
Use the balanced equations and the information given in the problem to solve for
the unknown quantity.
1. 2Cu
+
S

Cu2S
If you have 12.7 grams of copper, how many grams of sulfur would you need
to react completely?
3.2 grams of Sulfur
2. N2 +
2O2 
2NO2
How many grams of nitrogen are needed to react with 3.20 grams of oxygen
to create nitrogen dioxide?
1.4 grams of Nitrogen
3. HCl
+
NaOH 
H2O +
NaCl
How many mL of 4.0M HCl are needed to completely react with 250mL of
6.0M NaOH?
375 mL of HCl
4. HC2H3O2 +
NaHCO3

NaC2H3O2 +
CO2 +
H2O
How many mL of 0.10M acetic acid are needed to react with 5.0 g of
baking soda (NaHCO3)?
595 mL of vinegar
5. 2CH3OH +
3O2 
2CO2 +
4H2O
The methyl alcohol, CH3OH(l), used in alcohol burners combines with
oxygen gas to form carbon dioxide and water. How many grams of oxygen are
required to burn 34.2 g of methyl alcohol?
51.3 grams of oxygen
Limiting Reagent Calculations
1. Consider a reaction with 151.7 g of iron and 232.3 g of chlorine gas react, iron
(III) chloride is produced.
A) Write the balanced equation for the reaction.
2 Fe + 3 Cl2  2 FeCl3
B) Identify the moles of each reactant.
2.72 mol Fe & 3.28 mol Cl2
C) Identify the limiting reagent.
Cl2
D) Calculate the grams of product.
354 g FeCl3
E) Calculate the grams of excess reactant.
30 g Fe excess
2. If 31.0 g of aluminum is reacted with 46.7 g of bromine gas, then aluminum
bromide is formed.
A) Write the balanced equation for the reaction.
2 Al + 3 Br2  2 AlBr3
B) Identify the moles of each reactant.
1.15 mol Al & 0.292 mol Br2
C) Identify the limiting reagent.
Br2
D) Calculate the grams of product.
52 g AlBr3
E) Calculate the grams of excess reactant.
25.8 grams Al