This document contains 5 chemistry problems involving stoichiometry calculations: 1) Determining empirical formulas from elemental compositions. 2) Calculating molecular formulas from empirical formulas and molar masses. 3) Balancing a chemical equation and calculating amounts of reactants and products. 4) Identifying limiting reactants, calculating moles of products, and excess reactants. 5) Calculating theoretical and percent yields of a reaction.

1. GENERAL CHEMISTRY-I (1411)
S.I. # 11
1. Determine the empirical formula of each of the following compounds with the
following compositions by mass:
a. 55.3% K, 14.6%P and 30.1%O
b. 24.5% Na, 14.9% Si, and 60.6% F
2. What is the molecular formula of each of the following compounds?
a. empirical formula HCO2, molar mass = 90.0 g/mol
b. empirical formula C2H4O, molar mass = 88 g/mol
3. Given: Fe2O3 (s) + CO (g)  Fe (s) + CO2 (g)
a. Balance this equation, what are the coefficients? ____ _____ _____ _____
b. Calculate the number of grams of CO that can react with 0.150 kg of Fe2O3.
c. Calculate the number of grams of Fe and the number of grams of CO2 formed
when 0.150 kg of Fe2O3reacts.

2. 4. Aluminum Hydroxide reacts with sulfuric acid as follows:
2 Al (OH)3 (s) + 3 H2SO4 (aq)  Al2(SO4)3 (aq) + 6 H2O (l)
a.Which reagent is the limiting reactant when 0.500 mol Al(OH)3 and 0.500 mol
H2SO4 are allowed to react?
b. How many moles of Al2(SO4)3 can form under these conditions?
c. How many moles of the excess reactant remain after the completion of the
reaction?
5. Given: C2H6 + Cl2  C2H5Cl + HCl
a. Calculate the theoretical yield of C2H5Cl, when 125g of C2H6 reacts with 255g Cl2.
b. Calculate the percent yield of C2H5Cl if the reaction produces 206g of C2H5Cl.