Name: ________________________________
Unit 4 Monster Problem and Review
Date: _______________
You are performing a combustion reaction with an unknown liquid hydrocarbon. Chemical analysis shows that the
compound is 88.8% Carbon and 11.2% Hydrogen by mass. The molar mass is 108.2 g/mol. You perform this
reaction with 51.000 grams of the unknown hydrocarbon and 41.000 grams of oxygen gas, producing 11.320
grams of water. Find the following:
The empirical formula of the unknown hydrocarbon.
The molecular formula of the unknown hydrocarbon.
The balanced chemical reaction including states of matter.
How many moles of the unknown hydrocarbon were present before the reaction.
How many grams of the unknown hydrocarbon were present before the reaction.
How many representative particles of the unknown hydrocarbon were present before the reaction.
The limiting reagent.
The theoretical yield of the reaction.
The percent yield of your reaction.
How much of the excess reagent remains after the reaction.
Name: ________________________________
Unit 4 Monster Problem and Review
Date: _______________
1. Give the percentage composition for each compound:
a) H2SO4
2. Calculate the molar mass of
b) Fe2(Cr2O7)3
a) (NH4)2SO4
b) Ca(OH)2
3. a) How many moles are in 16.0 grams of CuCl2?
b) How much does 7.00 moles of NaCl weigh?
4. a) How many molecules are in exactly 4.0 moles of H2O?
b) How many hydrogen atoms are in 0.173 moles of H2O?
5. What mass of magnesium oxide results when 56.3 g O2 combines with excess magnesium?
6. Label as simplest formula, molecular formula, or both: a) CuCl2
b) CO2
c) O2 d) C4H10.
7. A substance is 80% C and 20% hydrogen by mass. a) What is the empirical formula? b) What is the
molecular formula of the compound if the molar mass is 30.0 g/mol?
8. Balance these equations: a) C4H8 + O2 → CO2 + H2O
b) H2O + Al4C3 → CH4 + Al(OH)3
9. Given the reaction 3O2 + 4NH3 → 2N2 + 6H2O, if 20.58 g of O2 combines with 26.0 g NH3 …
a) What is the limiting reagent?
b) What mass of water can theoretically form?
c) If 15.0 g of water is the actual yield, what is the percentage yield?
10. In a reaction, copper is heated with sulfur, forming cuprous sulfide (copper I sulfide). What is the
percent yield if 97.0 g of cuprous sulfide forms from the combination of 100.0 g of Cu with 50.0 g of
sulfur?