Question

Please complete the calculations and show all steps.

ic at the niseet When the small circles on each cursor line overlap each eht tu ie potht Where inction, the temperatures shown in either examine box should be equal to the intersect DATA AND CALCULATIONS Mass of lauric acid Mass of benzoic acid Freezing temperature of pure lauric acid Freezing point of the benzoic acid-lauric acid mixture Freezing temperature depression, At 43.0 sq.5 oC °C °C Molality, m molkg Moles of benzoic acid mol Molecular weight of benzoic acid (experimental) g/mol Molecular weight of benzoic acid (accepted) g/mol Percent error

Answer 1

Freezing point depression = 42.29-39.5 = 2.79°C

Molality = ∆t/k = 2.79/3.9 = 0.72

Moles of benzoic acid = Molality×mass of lauric acid (Kg)

= 0.72×0.008003 = 0.00574 moles

Molecular weight (exp.) = mass/moles = 1/0.00574

= 174 g/mol

Molecular weight (acc.) = 7C + 6H +2O

=7×12+6×1+2×16 = 122 g/mol

%error = (174-122)/122 ×100 = 42.6%