Question

12.
A bottle of 1 litre capacity is labelled as 1 molar Al(SO.). (aq). If the bottle is half filled and density of solut
1.342 g/ml, molality of Al- (aq) in this solution will be :
(A) 1
(B)2
(C) 3
(D) 4​

Answer 1

Molality of Al- = 2

Explanation:

Given: A bottle of 1 litre capacity is labelled as 1 molar Al2(SO4)3 (aq). The bottle is half filled and density of solution is 1.342 g/ml.

Find: Molality of Al- (aq) in this solution

Solution:

Volume = 500 ml = 1/2 liter

Density of the solution = 1.342 g/ml.

density = mass / volume

So mass = density * volume = 1.342 * 1/2 = 0.671 g

Molar mass of Al2(SO4)3 = 342 g

Molality of Al- = 0.671 / 342 * 1000 = 2

Option B is the answer.

Answer 2

$\Huge \tt(B) \: \: 2$