This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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5. (a) (iii) Equation for the laboratory preparation of chlorine: MnO_2(s) + 4HCl(aq) MnCl_2(aq) + Cl_2(g) + 2H_2O(l) 5. (b) (i) Equation for the reaction of chlorine with hot concentrated sodium hydroxide solution: 3Cl_2(g) + 6NaOH(aq) hot, conc. NaClO_3(aq) + 5NaCl(aq) + 3H_2O(l) (ii) The products of the reaction of chlorine with hot concentrated sodium hydroxide solution are: • Sodium chlorate(V) • Sodium chloride • Water (iii) When moist blue litmus paper comes in contact with chlorine, it first turns red and then is bleached (turns white). (iv) Calculate the volume of chlorine at s.t.p. Given equation: Ca(OH)_2(s) + Cl_2(g) CaOCl_2(s) + H_2O(l) Given: Mass of Ca(OH)_2 = 3.70 g. Relative atomic masses: H=1, O=16, Ca=40. Molar volume at s.t.p. = 22.4 dm^3/mol. Step 1: Calculate the molar mass of Ca(OH)_2. Molar mass of Ca(OH)_2 = 40 + 2(16+1) = 40 + 2(17) = 40 + 34 = 74 g/mol Step 2: Calculate the moles of Ca(OH)_2. Moles of Ca(OH)_2 = MassMolar mass = 3.70 g74 g/mol = 0.050 mol Step 3: Use the stoichiometric ratio from the balanced equation. From the equation, 1 mole of Ca(OH)_2 reacts with 1 mole of Cl_2. Therefore, moles of Cl_2 required = 0.050 mol. Step 4: Calculate the volume of Cl_2 at s.t.p. Volume of Cl_2 = Moles × Molar volume at s.t.p. Volume of Cl_2 = 0.050 mol × 22.4 dm^3/mol = 1.12 dm^3 5. (c) (i) On warming ammonium trioxonitrate (V) (NH_4NO_3) with sodium hydroxide solution, a pungent-smelling gas (ammonia) is evolved, which turns damp red litmus paper blue. (ii) Ammonium trioxocarbonate (IV) ((NH_4)_2CO_3) leaves no residue on being heated because it decomposes completely into gaseous products (ammonia, carbon dioxide, and water vapor), leaving no solid behind. (NH_4)_2CO_3(s) 2NH_3(g) + CO_2(g) + H_2O(g) 6. (a) (i) To remove the sediment in a sample of water: Filtration. Pass the water through filter paper or a fine sieve to separate insoluble solid particles. (ii) To soften temporarily hard water without heating it: Clark's process (adding a calculated amount of calcium hydroxide). The calcium hydroxide reacts with soluble hydrogen carbonates to form insoluble calcium carbonate, which precipitates out. (iii) To obtain pure water from muddy water: Distillation. First, filter the muddy water to remove suspended particles, then boil the filtered water and condense the steam to collect pure water. (iv) To remove oxygen and moisture from a sample of air: To remove oxygen, pass the air over heated copper turnings. To remove moisture, pass the air through a drying agent such as concentrated sulfuric acid or anhydrous calcium chloride. 6. (b) (i) Alums are double salts. (ii) The function of alum in water treatment plants is as a *co