Question

Calculate the mass of the compound (molar mass = 256 ) be dissolved in 75 g of benzene to lower it's freezing point by 0.48 (kf= 5.12 k kg / mol)

Answer 1

Hi mate

Here is the answer

We know, Tf =0.48k

Kf =5.12 k kg / mol

W1 =75g

M2= 256 g/ mol

So, W2 =?

Now, Tf = Kf ×W2×1000/M2×W1

=>>W2 = Tf×M2×W1/Kf ×W2×1000

=>>W2 = 0.48×256×75/5.12×1000

=>>W2 = 18 Grams

HOPE IT HELPS

BE BRAINLY ///

Answer 2

Given :

M' (molar mass of solute)=256gmol^-1

W'( wt. of solute) = x

W ( wt of solvent ) = 75 g

Tf = 0.48 K and Kf = 5.12

Soln:

Tf = kf × w' × 1000 / M' × w

w' = 0.48 × 75 × 256 / 5.12 × 1000

w' = 1.80 gram

This is a actual answer .....