Choose the solvent below that would show the greatest boiling point elevation when used to make a 0.10 mol kg^-1 nonelectrolyte solution. A) CCl₄, K_b = 29.9 °C m^-1 B) C₆H₆, K_b = 5.12 °C m^-1 C) CH₃CH₂OCH₂CH₃, K_b = 1.79 °C m^-1 D) CH₃CH₂OH, K_b = 1.99 °C m^-1 E) CHCl₃, K_b = 4.70 °C m^-1

Question

Quizplus · Accepted Answer

The boiling point elevation is directly proportional to the molality (m) of the solution, which is in turn proportional to the number of moles of solute (n) divided by the mass of the solvent (m):
m = n / m
Since all the solvents have the same mass, the solvent with the greatest molality will have the greatest boiling point elevation. Therefore, we need to determine which solvent will have the greatest number of moles of solute for a given molality.
The molality of the solution is given as 0.10 mol kg-1, so for each solvent, we can calculate the number of moles of solute required to make a 1 kg solution:
A) CCl4: n = 0.10 mol
B) C16H16O: n = 0.10 mol
C) C26H22O2: n = 0.10 mol
D) C7H10O: n = 0.10 mol
E) CHCl3: n = 0.10 mol
Since all the solvents have the same molality of solute, the solvent with the greatest number of moles of solute will have the greatest boiling point elevation. Therefore, the solvent with the greatest molar mass will have the greatest number of moles of solute for a given molality. Solution A (CCl4) has the greatest molar mass, so it is the best choice.

Choose the Solvent Below That Would Show the Greatest Boiling