Question

If the freezing point of the solution had been incorrectly read 0.3degrees C lower than the true freezing point, would the calculated molar mass of the solute be too high or too low? Explain.

Answer 1

ΔTf = m*Kf*i, solving for molaity,

ΔTf/*Kf*i= m
molality= moles of solute/kg of solution.

Since, 1 mole= molecular weight,
I think decreasing the number of moles decreases the molecular weight.


But I can not be sure about this one.

Answer 2

(1) delta T = i*K*m
(2) m = mols/kg solvent
(3) mols= g/molar mass or
molar mass = g/mols.

T read too low makes delta T too high in 1. That makes m too high.

2. m too high in 2 means mols too high.

3. mols too high in 3 means molar mass too low.
I agree with Devron.