A student determines the freezing point of a solution of 1.96g of naphthalene in 25.64g of paradichlorobenzene(PDB). The following temperature-time reading are recorded.

Question

PDB/Napthalene
Time(Min) 0 0.5 1.5 2 2.5 3 3.5 4 4.5
Temp(°C) 59.7 58.0 54.8 53.4 52.1 50.9 49.5 49.6 49.5

a) Estimate the freezing Point of the solution from the above data_________°C

b) Taking the Kf for PDB to be 7.10, calculate the molecular weight of the solid. Assume 53°C to be the freezing point of pure PDB. MW______________________________
0 following

Answer 1

I would take 49.5 as the freezing point or you could use 49.5, 49.6 and 49.5, take the average as 49.53 which rounds to 49.5.

For #2, what is the solid? Is that Naphthalene (by the way, note the spelling) or is that the mixture of PDB and naphthalene.