Question

A. The boiling point of diethyl ether, CH3CH2OCH2CH3, is 34.500 °C at 1 atmosphere. Kb(diethyl ether) = 2.02 °C/m In a laboratory experiment, students synthesized a new compound and found that when 10.22 grams of the compound were dissolved in 249.9 grams of diethyl ether, the solution began to boil at 34.714 °C. The compound was also found to be nonvolatile and a non-electrolyte. What is the molecular weight they determined for this compound ?

B. The boiling point of benzene, C6H6, is 80.100 °C at 1 atmosphere. Kb(benzene) = 2.53 °C/m In a laboratory experiment, students synthesized a new compound and found that when 13.20 grams of the compound were dissolved in 269.2 grams of benzene, the solution began to boil at 80.450 °C. The compound was also found to be nonvolatile and a non-electrolyte. What is the molecular weight they determined for this compound ?

Answer 1

→ Given, B.p of solvent = 34.500°c kg = 2.02 cm Mall of solute = 10.229, Mase of solvent = 249.99 B. P of solution - 34.714°C since, by elevation in B.P: - Bip of solution - Bop of solvent = 34.714 - 34.500 AT - 0.214°C (1) Also, Atoa kpx. Mase of solute X 1000 Molar mall x hall of of solute solven olar mass = 2.02x 10.22x1000 of compound 0.214 x 249.9 = 386.03 g/mol. - - 6 Given, B.P of colvent = 80.100°c Ko = 2.53°clm. Most of solute = 13.209 Mase of B. P of solution = 80.450°C solvent = 267.2 g AT6 = 80.450-80.100 = 0.350°C By de Molar mass - 2.53X 13 20x 1000 0.350X 269.2. Molecular weight of compound - 354.44 g/n