1. Chapter 10 Chemical Calculations
REVISION

2. (a) Write the balanced equation for the reaction between sulphur and oxygen to form sulphur dioxide.
In one process, 4.0g of sulphur was burnt in 48.0dm3 of oxygen measured at r.t.p.
(b) What is the limiting reactant in this reaction?
(c) Calculate the volume of sulphur dioxide formed at r.t.p.

3. When 1. 92g of magnesium was heated in excess oxygen, 3
When 1.92g of magnesium was heated in excess oxygen, 3.0g of magnesium oxide was obtained.
Calculate the percentage yield of magnesium oxide.

4. Nitrogen and hydrogen react to form ammonia.
N2 (g) + 3H2 (g)  2NH3 (g)
12dm3 of hydrogen reacted with excess nitrogen to form 2dm3 of ammonia.
What is the percentage yield of ammonia at room temperature and pressure?
(1 mol of gas occupies 24dm3 at room temperature and pressure.)

5. 4NH3(g) + 5O2(g)  4NO(g) + 6H20(g)
Ammonia is used to produce nitric acid. The first step in the manufacturing process is the reaction between ammonia and oxygen to produce gaseous nitrogen monoxide (NO) and water vapour.
4NH3(g) + 5O2(g)  4NO(g) + 6H20(g)
(a) 1.0mol of ammonia gas was allowed to react with 1.0mol of oxygen. What is the limiting reactant in this reaction? (b) Using the number of moles given in (a), how many moles of each of the following will be formed? - Nitrogen monoxide - Water vapour
(c) Calculate the volume of nitrogen monoxide formed if 40cm3 of ammonia reacted with 60cm3 of oxygen.