Question

5 gm of CH₃COOH is dissolved in one litre of ethanol.
Suppose there is no reaction between them. If the density of
ethanol is 0.789 gm/ml then the molality of resulting solution
is
(a) 0.0256 (b) 0.1056 (c) 0.1288 (d) 0.1476

Answer 1

5 gm of CH₃COOH is dissolved in one litre of ethanol.

Suppose there is no reaction between them. If the density of

ethanol is 0.789 gm/ml then the molality of resulting solution

is 0.1056 m

- given : w = 5 gm

Mol wt of CH3COOH= 60 gm

Volume of ethanol = 1 litre = 1000ml

Density of ethanol = 0.789 gm/ml

-mass of ethanol = volume × density

W = 1000 ml × 0.789 gm/ml

W = 789 gm

- molality = (w × 1000)/ (Mol. wt × W)

= (5 × 1000)/ (60 × 789)

m = 5000/ 47340

m = 0.1056 m

- so the correct option is (b)