question_answer 37)

Calculate the molality of a solution of ethanol in water in which the mole fraction of ethanol is 0.04.

Answer:

We know \[m=\frac{{{x}_{B}}\times 1000}{(1-{{x}_{B}}){{m}_{A}}}\] (i) \[{{x}_{B}}=\] Mole fraction of solute = 0.04 \[{{m}_{A}}=\] Molar mass of solvent = 18 Putting these values in Eqn. (i), we get \[m=\frac{0.04\times 1000}{(1-0.04)\times 18}=2.31\]