Experiment 4 Freezing Point Depression 1 Would your experime

Experiment 4

Freezing Point Depression

1. Would your experimental results be too high or too low if the following problems happened?        Circle you answers.  

Some of the solvent is lost (for whatever reason).

molality          higher    lower    unchanged               Explain:

T_f                  higher    lower    unchanged

T_f                     higher    lower    unchanged

Molar mass     higher    lower    unchanged

Solution

Expertiment 4 : Depression in freezing point

Formula,

dTf = -i.Kf.m

with,

i = van\'t hoff factor

Kf = constant

m = molality = grams solute/molar mass x kg of solvent

1. If some of the solvent is lost

molality         : higher (as mass of solvent decreases in the denominator of molality formula, molality would increase)

dTf                : higher (molality and dTf are directly proportional to each other)

Tf                  : remains unchanged (as it is independent of molality)

Molar mass  : lower (molality and molar mass are inversely proportional to each other)