Question

A solution contains 35 grams of KNO3 dissolved in 100 grams of water at 40°C. How much more KNO3 would have to be added to make it a saturated solution?
(1) 29 g (3) 12 g
(2) 24 g (4) 4 g

Answer 1

The answer is (1) 29 g. The solubility means that one compound can be dissolved in 100 grams of water. The solubility of KNO3 under 40℃ is 64 g. So 64-35=29 grams of KNO3 needs to be added.

Answer 2

The solubility of  at 40 C is around 64 g in 100 g water  ot 0.64 g KNO3 in 100 g water.  

Therefore 64 g KNO3  in 100 g water is required for satured solution.

 According to the problem  there are 35 grams of KNO3 dissolved in 100 grams  water  

So we need 64 g-35 g= 29 g more KNO3  

Hence the correct answer is 1  

Solubility:

When the maximum amount of solute is dissolve in the solvent is called solubility. On the basic of solubility the solution are following types:

Saturate solution:

A solution which contains the maximum amount of dissolved solute at the equilibrium is called saturated solution.  

Un-saturate solution:

A solution which contains lesser amount of solute as compare to saturated solution.  It will be able to dissolver more solute.  

Super -Saturate solution:

A solution which contains the more dissolved amount of solute as compare to saturated solution.