Question

The solubility of potassium nitrate is 32% at 20°C. What mass of KNO3, would be needed to
produce a saturated solution using 50 g water at 70°C.​

Answer 1

Explanation:

Since, solubility is expressed as amount of solute in 100 gm of solvent so,

We have at 20°C ,100 gm water dissolve 32 gm KNO3.

50 gm water will have, = (32/100) x50 = 16 gm of KNO3.

Now, solubility of KNO3. increases with increase in temperature, which can be given by solubility graph only, as the graph is not given so, we can say that, if

50 gm water contains 16 gm of KNO3. at 20°C,

The amount must be 70/20 = 3.5 times multiple (nearly) of the above amount at 20°C

So, the expected amount is =16 x 3.5 =56 gm

[Normally, the graph curve of KNO3. increases and so it is taken as multiple of the temperature intervals, you may take some graphs given in various books to have the clear concept.]

All the best!