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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Here's the solution to question 5: 5. (a) i) The names of two allotropes of sulfur are rhombic sulfur and monoclinic sulfur. ii) When hydrogen sulfide is bubbled through acidified potassium tetraoxomanganate (VII) solution, the purple solution turns colorless and a yellow precipitate (sulfur) is formed. This is because hydrogen sulfide reduces the purple manganate(VII) ion to the colorless manganese(II) ion, while being oxidized to sulfur. iii) The products of the reaction of sulfur (IV) oxide with hydrogen sulfide are sulfur and water. 2H_2S(g) + SO_2(g) 3S(s) + 2H_2O(l) 5. (b) i) The raw materials for the manufacture of tetraoxosulphate (VI) acid by the contact process are sulfur, air (as a source of oxygen), and water. ii) The reaction that requires a catalyst in the contact process is the oxidation of sulfur dioxide to sulfur trioxide. 2SO_2(g) + O_2(g) 2SO_3(g) The catalyst used is vanadium(V) oxide (V_2O_5). iii) I. When concentrated H_2SO_4 reacts with copper turnings: • Observation: The copper turnings dissolve, forming a blue solution, and a pungent, colorless gas (sulfur dioxide) is evolved. • Product formed: Copper(II) sulfate (CuSO_4). II. When concentrated H_2SO_4 reacts with a cube of sugar: • Observation: The white sugar turns black and swells up into a porous mass of carbon, with steam being evolved. • Product formed: Carbon (charcoal). 5. (c) i) Three uses of sodium trioxocarbonate (IV) are: • In the manufacture of glass. • For softening hard water. • In the manufacture of soap and detergents. ii) The name given to the reaction Na_2CO_3 · 10H_2O(s) exposure to air Na_2CO_3 · H_2O(s) + 9H_2O(g) is efflorescence. iii) Calculation of the solubility of Na_2CO_3: Step 1: Identify the given values. Mass of anhydrous salt = 1.75 g Volume of saturated solution = 20.0 cm^3 Step 2: Calculate the solubility per 100 cm^3 of solution. Solubility = Mass of soluteVolume of solution × 100 cm^3 Solubility = 1.75 g20.0 cm^3 × 100 cm^3 Solubility = 0.0875 g/cm^3 × 100 cm^3 Solubility = 8.75 g/100 cm^3 The solubility of Na_2CO_3 at 25°C is 8.75 g/100 cm^3. That's 2 down. 3 left today — send the next one.