Question

The weight of an empty china dish is 39 g and when a saturated solution of potassium nitrate is poured into, its weight is 108 g at ${50}^{\circ }C$. After evaporating the solution to dryness, if the weight of the dish along with the crystals is 72 g then the solubility of potassium nitrate at ${50}^{\circ }C$ is .....................

• A. $83.9$
• B. $95.6$
• C. $91.6$
• D. $87.4$

Answer 1

The correct option is C $91.6$

The formula for calculating the solubility can be written as:
$\frac{Massofsalt\left(g\right)}{Massofwater\left(g\right)}=\frac{Solubilityofsalt}{100gwater}$
Mass of saturated solution of $KN{O}_3$ = 108 - 39 = 69g
Mass of water = $108-72g=36g$

Mass of $KN{O}_3$ =$69-36=33g$

$\therefore$ Solubility of $KN{O}_3$ = $\frac{33\times 100}{36}$ = 91.6