Chapter 7 Stoichiometry Worksheet 1

1 Chapter 7 Mole Concept and Stoichiometry 3E Chapter 7 Mole Concept and Stoichiometry Worksheet One 1. In an experiment, 4.0 g of sulfur was burnt in 48.0 dm3 of oxygen measured at r.t.p to form sulfur dioxide. (a) Write the equation for the reaction between sulfur and oxygen. ………………………………………………………………………………………………………………… (b) What was the limiting reactant in this reaction? (c) Calculate the volume of sulfur dioxide formed at r.t.p. Ans: (b) S (c) 3.00 dm3

2 Chapter 7 Mole Concept and Stoichiometry 2. (a) A compound contains 40.0% carbon, 6.70% hydrogen and 53.3% oxygen. What is its empirical formula? (b) Given that the compound has an Mr of 180, find its molecular formula. Ans: (a) CH2O (b) C6H12O6

3 Chapter 7 Mole Concept and Stoichiometry 3. In an experiment, 1.20 g of magnesium was reacted with excess hydrochloric acid. Magnesium chloride and hydrogen gas were produced. (a) Write a balanced chemical equation for this reaction. ………………………………………………………………………………………………………………… (b) Calculate the mass of magnesium chloride produced in this reaction. (c) Calculate the volume of hydrogen gas produced at room temperature and pressure. Ans: (b) 4.75 g (c) 1.20 dm3

4 Chapter 7 Mole Concept and Stoichiometry 4. (a) Define relative atomic mass. ………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………… (b) Define relative molecular mass. ………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………… (c) Calculate the relative molecular mass of the following substances. MgCl2 NaOH H2SO4 Nitrogen Gas Ans: (Refer to solutions)

5 Chapter 7 Mole Concept and Stoichiometry 5. A magnesium ribbon was loosely coiled and placed in a weighed crucible. The crucible was heated to allow the magnesium to react with oxygen in the air to form magnesium oxide. Mass of Crucible / g : 20.10 Mass of Crucible With Magnesium / g : 20.58 Mass of Crucible With Magnesium Oxide / g : 20.90 (a) Write a balanced chemical equation for this reaction. ………………………………………………………………………………………………………………… (b) Calculate the mass of magnesium ribbon used. (c) Find the volume of oxygen that reacted. Ans: (b) 0.48 g (c) 0.24 dm3