Question

if the liquid did not completely vaporize in the experiment would the apparent molecular weight by larger, smaller or unchanged compared to that determined if the experiment had been properly performed?

Answer 1

Determination of molecular mass.

If the liquid is not completely vaporized during the experiment, the pressure generated in the flask will be very low. Thus, low pressure in the flask gives a lower number of moles.

Using ideal gas equation, pV = nRT

            “Pressure, P” is directly proportional to “number of moles”           -- statement 1

            A low value of “P” also gives “low value of n”.

Noe,

Molecular mass = Mass of solute / number of moles                               

Molecular mass is inversely proportional to number of moles, n                -- statement 2

Compare statement 1 and 2-

            Molecular mass is inversely proportional to pressure.                   -- statement 3

Therefore, a low value of Pressure obtained due to partial vaporization result HIGHER apparent molecular mass of the solute.