Worksheet Set B Worksheet B002 (K. Nel - 2012) A. Physical and Chemical change 1. Write equations for the following reactions: a. 2 moles of copper atoms combine with 2 moles of sulfur atoms to form 2 moles of copper(II) sulphide 2πΆπ’ + 2π → 2πΆπ’π b. 1 mole of iron(III) oxide (Fe2O3) reacts with 3 moles of hydrogen molecules to form 2 moles of iron atoms and 3 moles of water molecules. πΉπ2 π3 + 3π»2 → 2πΉπ + 3π»2 π c. 1 mole of ethanol molecules (C2H5OH) burns in 3 moles of oxygen molecules to form 2 moles of carbon dioxide molecules and 3 moles of water molecules. πΆ2 π»5 ππ» + 3ππ»2 → 2πΆπ2 + 3π»2 π 2. Balance the following equations: a. 1Cl2(g) + 2KBr(aq) → 2KCl(aq) + 1Br2(aq) b. 1Zn(l) + 1F2O3(l) → 2Fe(l) + 3ZnO(s) c. 1Pb(NO3)2(s) → 1PbO2(s) + 2NO2(g) + O2(g) d. 1C2H5OH(l) + 1O2(g) → 1CO2(g) + 1H2O(l) e. 2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g) 3. When calcium carbonate is heated strongly, the following change occurs: CaCO3(s) → CaO(s) + CO2(g) a. Write a word equation for this change Calcium Carbonate ο Calcium Oxide + Carbonate b. How many moles of CaCO3 are there in 75g of calcium carbonate? Caο 40g O=16g C=12g πΆππΆπ3 → 40π + 12π + 16,3π = 100g 75 g of πΆππΆπ3 = 0,75 mole c. What mass of calcium oxide is obtained from the thermal decomposition of 75g of calcium carbonate? Assume a 45% yield. Ca=40g O=16g (40π+16π)π₯75 100 = 42π d. What mass of carbon dioxide will be given off simultaneously (at the same time)? 75g – 42g = 33g e. What volume will this gas occupy at rtp? 1 mole of gas = 24ππ3 0,75 mole of gas = 18ππ3 4. 8g of impure magnesium carbonate reacts with an excess of hydrochloric acid as shown below: MgCO3(s) + 2HCl(aq) → MgCl2(aq) + H2O + CO2(g) 1325 cm3 of carbon dioxide is collected at rtp. a. How many moles of carbon dioxide are produced? 1 mole of πΆπ2 = 24000ππ3 = 1025 ππ3 1325ππ3 24000ππ3 = 0,05 ππππ of πΆπ2 released. b. What mass of pure magnesium carbonate would give this volume of carbon dioxide? 1 mole of MgCO3 = Mg = 24g C = 12g 24g + 12g +(16g x3) = 84g O = 16g 84g x 5/100 = 4,2g (Pure MgCO3) c. Calculate the %purity of this magnesium carbonate. 4,2π π₯100 = 52,5% ππ ππ’ππ ππ MgCO3 8π --------------------------------------------------------------------