Question

The solubility curve of KNO${}_3$ as a function of temperature is given above
The amount of KNO${}_3$ that will crystallize when a saturated solution of KNO${}_3$ in 100 ml of water is cooled from 90${}^o$C to 30${}^o$C, is

• A. 16 g
• B. 100 g
• C. 56 g
• D. 160 g

Answer 1

Answer: (D)

160 g

So, from the given curve, $KN{O}_3$ has a

solubility of $210g$ per $100ml$ of water

at ${90}^{\circ }C$

Now, at ${30}^{\circ }C$ solubility of $KB{O}_3$ is

$50g$ per $100ml$ of water

After cooling the water from ${90}^{\circ }C$ to ${30}^{\circ }C$

the amount of crystallized $KN{O}_3$ per $100ml$

of water is

$(210-50)g=160g$ per $100ml$ of water