Worksheet 3 – Chapter 3 , Part 2

1. Potassium reacts with oxygen to make potassium oxide, K2O. What is the maximum mass (g) of K2O(s) that could be prepared from 8.16 g of K(s) and 2.66 g of O2(g)?

2. Aluminum and oxygen react to form aluminum oxide.

In a certain experiment, 4.6 g Al was reacted with excess oxygen and 6.8 g of product wasobtained. What was the percent yield of the reaction?

3. Calcium reacts with sulfur forming calcium sulfide. What is the theoretical yield (g) of CaS(s) that could be prepared from 7.72 g of Ca(s) and 2.24 g of sulfur(s)?

4. A sample of impure magnesium was analyzed by allowing it to react with excess HCl solution:

Mg(s) + 2HCl(aq) => MgCl2(aq) + H2(g)

After 1.32 g of the impure metal was treated with 0.100 L of 0.750 M HCl, 0.0125 mol HClremained. Assuming the impurities do not react with the acid, what is the mass % Mg in thesample?