# Problem: Sulfuric acid in water dissociates completely into H+ and HSO4- ions. The HSO4- ion dissociates to a limited extent into H+ and SO42-. The freezing point of a 0.1000 m solution of sulfuric acid in water is 272.72 K.Calculate the molality of SO42- in the solution, assuming ideal solution behavior.

95% (13 ratings)
###### FREE Expert Solution

We’re being asked to find the molality of SO42- solution assuming ideal behavior.

When calculating the freezing point of a solution, we’re going to use the equation for Freezing Point Depression.

$\overline{){\mathbf{∆}}{{\mathbf{T}}}_{{\mathbf{f}}}{\mathbf{=}}{\mathbf{i}}{\mathbf{·}}{{\mathbf{K}}}_{{\mathbf{f}}}{\mathbf{·}}{\mathbf{m}}}$

∆Tf = change in freezing point = Tf pure solvent –Tf solution
Kf = freezing point depression constant
i = van' t Hoff factor of the solute = no. of ions
m = molality

Recall that the formula for molality is:

Determine the required values for the Freezing Point Depression equation:

95% (13 ratings)
###### Problem Details

Sulfuric acid in water dissociates completely into H+ and HSO4- ions. The HSO4- ion dissociates to a limited extent into H+ and SO42-. The freezing point of a 0.1000 m solution of sulfuric acid in water is 272.72 K.

Calculate the molality of SO42- in the solution, assuming ideal solution behavior.