The mass of cyclohexane that was dispensed can be calculated. The density of cyclohexane is 0.779 g/mL.

The values for T_f° and T_f can be determined from the plots.

The molar mass, and thus the molecular weight, of the unknown compound can also be calculated. For cyclohexane, Kf = 20.2 °C kg/mole of solute.

molar mass = ? g/mol

molecular weight = ? amu

The molecular weights of the possible compounds are:

• 154.21 amu for Biphenyl
• 191.46 amu for 2-Bromochlorobenzene
• 128.17 amu for Naphthalene
• 178.23 amu for Anthracene
• 235.90 amu for 1,4-Dibromobenzene

The value determined experimentally for the molecular weight of the unknown compound is closest to the literature value for naphthalene.

The percent error can be calculated.

& error = ? %