How do you calculate number 1a? The following data were obtained in an experimen

Question

How do you calculate number 1a? The following data were obtained in an experiment designed to find the molar mass of a solute by freezing point depression. Solvent: para-dichlorobenzene Freezing point depression constant: 7.1 degree C/m Freezing point of pure solvent: 53.02 degree C Mass of para-dichlorobenzene: 24.80 g Mass of unknown substance. 2.04 g Freezing point of solution: 50.78 degree C Determine the freezing point depression, delta T_fp. Using Equation calculate the molar mass of the unknown substance.

Explanation / Answer

1a)

to calculate the depression in freezing point we were gien with frezzing point of solvent and solution.

Delta T f = F.P. of solvent - F.P. of solution

= 53.02 - 50.78 = 2.24

1b) we know the relation as

delta Tf = Kf . molality

= Kf x [weight of solute x 1000] / [ molar mass x weight f solvent]

substituting the given values

2.24 = 7.1 x 2.04 x 1000 / [ M x 24.8]

Solving for M

M = 260.72

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