Neco Model Questions Vol1 2022 Chemistry Question 8

A student carries out a solubility experiment to determine the solubility of calcium hydroxide, Ca(OH)₂, in water at two temperatures using the apparatus shown. The apparatus consists of a 250 mL beaker placed on a thermostatically controlled water bath, a thermometer, a magnetic stirrer, a filter funnel with filter paper, a pre‑weighed evaporating dish placed on an analytical balance, and a drying oven. The procedure is: 1. Measure 100.0 mL of distilled water into the beaker and adjust the water bath to the required temperature. 2. Add excess solid Ca(OH)₂ and stir until no further solid dissolves (saturation). 3. Filter the hot mixture through the funnel into a clean flask. 4. Transfer the filtrate to the evaporating dish, evaporate to dryness in the oven and cool in a desiccator. 5. Weigh the evaporating dish with the dried solute. The mass of the empty evaporating dish is 15.000 g. After the 25 °C experiment the mass of the dish plus dried solute is 15.300 g. After the 60 °C experiment the mass of the dish plus dried solute is 15.420 g. Answer the following questions: