Question

The solubility of potassium nitrate at 20c is 250ml . calculate the mass of potassium nitrate .we must dissolve in 400ml of water having a saturated solution at 20c

Answer 1

A mass 80g of $KNO_3$ dissolves in 250ml of water at 20°C

xg mass of $KNO_3$ dissolves in 400ml

x =$\dfrac{400×80}{250}g = 128g$

$\therefore$ The mass of potassium nitrate we must dissolve in 400ml of water at 20°C is 128g.