Worksheet Chapter 3: The Mole Concept, Chemical Formulae and Equations

1. Fill in the blank: The number of particles contained in 1 mole of any substance is known as the ________ constant.

2. Copper(II) carbonate decomposes upon heating according to the equation: CuCO3 (s) -> CuO (s) + CO2 (g) If 12.4 g of CuCO3 is heated completely, calculate the volume of CO2 gas liberated at room conditions. [RAM: Cu=64, C=12, O=16; Molar volume at room conditions = 24 dm3 mol-1]

3. True or False: One mole of oxygen gas (O2) and one mole of carbon dioxide gas (CO2) occupy the same volume under the same temperature and pressure.

4. Calculate the relative formula mass (Fr) of ammonium sulfate, (NH4)2SO4. [Relative atomic mass: N=14, H=1, S=32, O=16]

5. Define the term 'molar volume of gas' and state its value at room conditions.

6. 8.0 g of copper(II) oxide powder reacts completely with dilute sulfuric acid according to the following balanced equation: CuO (s) + H2SO4 (aq) -> CuSO4 (aq) + H2O (l) (a) Calculate the number of moles of CuO reacted. (b) Determine the mass of copper(II) sulfate formed. (c) If the experiment yields 14.4 g of copper(II) sulfate crystals, calculate the percentage yield. [RAM: Cu=64, O=16, H=1, S=32]

7. Explain step-by-step why the combustion method using a crucible is suitable for determining the empirical formula of magnesium oxide, but UNSUITABLE for determining the empirical formula of lead(II) oxide.

8. True or False: The molecular formula and empirical formula of water (H2O) are identical.

9. Which experimental set-up is used to determine the empirical formula of reactive metals such as zinc or magnesium?

10. A sample of oxide of iron contains 1.12 g of iron and 0.48 g of oxygen. Determine the empirical formula of this iron oxide. [RAM: Fe=56, O=16]