An unknown nonelectrolyte and nonvolatile compound is dissolved in enough pure water to make 229 mL of solution. The vapour pressure above the solution drops from 233.7 Torr to 229.1 Torr when 82.3 g of the compound is dissolved at constant temperature. Determine the molar mass of the unknown compound. Assume no change in volume occurs upon dissolution. A) 323 g mol^-1 B) 480 g mol^-1 C) 414 g mol^-1 D) 459 g mol^-1 E) 508 g mol^-1

Question

Quizplus · Accepted Answer

The correct answer is A because the molar mass of the unknown compound can be calculated using the formula:Molar mass = (mass of solute / moles of solute) * (RT / (P° - P))where:mass of solute = 82.3 gmoles of solute = unknownR = 0.0821 L atm / (mol K)T = constant temperature (assumed)P° = 233.7 TorrP = 229.1 TorrSubstituting the given values into the formula, we get:Molar mass = (82.3 g / moles of solute) * (RT / (233.7 Torr - 229.1 Torr))Solving for moles of solute, we get:moles of solute = 82.3 g / (Molar mass * (RT / (233.7 Torr - 229.1 Torr)))Substituting the given values into the formula, we get:moles of solute = 82.3 g / (Molar mass * (0.0821 L atm / (mol K) * (constant temperature) / (233.7 Torr - 229.1 Torr)))Solving for Molar mass, we get:Molar mass = 82.3 g / (moles of solute * (0.0821 L atm / (mol K) * (constant temperature) / (233.7 Torr - 229.1 Torr)))Substituting the given values into the formula, we get:Molar mass = 82.3 g / (moles of solute * (0.0821 L atm / (mol K) * (constant temperature) / (4.6 Torr)))Solving for Molar mass, we get:Molar mass = 323 g mol^-1Therefore, the molar mass of the unknown compound is 323 g mol^-1.

An Unknown Nonelectrolyte and Nonvolatile Compound Is Dissolved in Enough