WAEC SSCE - Chemistry - 2008 (Objective)

Question 1 Report

When 100 cm³ of a saturated solution of KCIO₃ at 40^oC is evaporated, 14 g of the salt is recovered what is the solubility of KCIO₃ at 40^oC? [KCIO₃ = 122.5]

11.42 mol dm^-3

8.80 mol dm^-3

1. 14 mol dm^-3

0.88 mol dm^-3

Answer Details

The solubility of a substance is the amount of the substance that can be dissolved in a given amount of solvent at a particular temperature. In this question, we are given that 100 cm³ of a saturated solution of KCIO₃ at 40^oC was evaporated to recover 14 g of the salt. This means that the remaining solution was no longer saturated and all of the excess KCIO₃ had precipitated out. To find the solubility of KCIO₃ at 40^oC, we can use the formula: Solubility = (mass of solute recovered) / (volume of solution before evaporation) The mass of KCIO₃ recovered is given as 14 g, and the volume of solution before evaporation is 100 cm³ or 0.1 dm³. We can calculate the number of moles of KCIO₃ using the given molar mass of KCIO₃: Number of moles = (mass of KCIO₃) / (molar mass of KCIO₃) = 14 / 122.5 = 0.114 moles Now, we can calculate the solubility of KCIO₃: Solubility = (mass of solute recovered) / (volume of solution before evaporation) = (0.114 moles) / (0.1 dm³) = 1.14 mol dm^-3 Therefore, the solubility of KCIO₃ at 40^oC is 1.14 mol dm^-3. The correct option is: - 1.14 mol dm^-3

Read lesson note on Solubility (JAMB)

Read lesson note on Solubility Of Substances (Ghana Only) (WAEC)






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