Question

17. What is the boiling point of 1 molal aqueous solution of NaCl [Ko = 0.52 k molar]
(1) 99.48°C
(2) 98.96°C
(3) 100.52°C
(4) 101.04°C

Answer 1

The boiling point of 1 molal aqueous solution of NaCl [Ko = 0.52 k molar] is:

(3) 100.52°C

According to the molal elevation constant formula,

ΔTb = Kb × m

where ΔTb is the elevation in boiling point

Kb is the molal elevation constant = 0.52 K molar.

m is the molality of the solution = 1 molal.

Putting the values in the above equation, we get

ΔTb = 0.52 × 1 = 0.52K = 0.52° C

Thus, the elevation in boiling point will be = ΔTb = 0.52° C

The boiling point of water is Tb = 100° C

So, the boiling point of 1 molal aqueous solution of NaCl [Kb = 0.52 k molar] is :

Tb + ΔTb = 100° C + 0.52° C = 100.52 °C

100.52°C