Question

$50{\text{ g}}$ of a saturated aqueous solution of potassium chloride at ${30^0}C$ is evaporated to dryness, when $13 \cdot 2{\text{ g}}$ of ${\text{KCl}}$ was obtained. Calculate the solubility of ${\text{KCl}}$ in water at ${30^0}C$.

Answer 1

Hint: The solution given is saturated aqueous means it contains water and fully dissolved the ${\text{KCl}}$ compound. The water part is evaporated which means one can find out the values of the remaining mass can be compared to mass that has been evaporated and final solubility can be calculated.

Complete step by step answer:
1) First of all let us learn about the concepts given question one by one and relate those to find out the correct solution for the given question. The saturated solution can be explained as a solution that contains the maximum amount of solute which can be dissolved in that solvent.
2) Now let us understand what solubility means where it is the property of the chemical substance of solid, liquid, or gas called solutes to dissolve in a solid, liquid, or gaseous state solvent.
3) Now that the solution containing ${\text{KCl}}$ was evaporated by the application of heat and the remaining amount of ${\text{KCl}}$ obtained is $13 \cdot 2{\text{ g}}$ we can calculate the evaporated water amount by subtracting it from the total amount as follows,
${\text{Mass of water = 50 - 13}} \cdot {\text{2 = 36}} \cdot {\text{8 g}}$
4) Now that we have got the amount of water mass we can now calculate the solubility by using the following formula,
${\text{Solubility of KCl in water = }}\dfrac{{{\text{Mass of KCl obtained}}}}{{{\text{Mass of water evaporated}}}} \times 100$
${\text{Solubility of KCl in water = }}\dfrac{{13 \cdot 2}}{{36 \cdot 8}} \times 100 = 0 \cdot 3586 \times 100 = 35 \cdot 86$
5) Therefore, the solubility of ${\text{KCl}}$ in water at ${30^0}C$ is $35 \cdot 86$.

Note:
The solubility of a substance is dependent on the nature of the solute and solvent. Solubility also depends on physical factors such as temperature and pressure. As the solubility is the number of grams dissolved per number of grams it doesn’t show any unit. The solubility concept should not be confused with the ability of a solution to dissolve a substance as both are different aspects.