Question

Choose the aqueous solution with the lowest vapor pressure. These are all solutions of nonvolatile solutes and you should assume ideal van't hoff factors where applicable. Which of the following solutions has the lowest vapor pressure?

1) 0.040 M (NH₄⁺)₂SO₄
2) 0.060 M Rb2NO₃
3) 0.030 M RbC₂H₃O₂
4) 0.120 M C₂H₆O₂

Answer 1

The solution with the lowest vapor pressure is 0.040 M (NH₄⁺)₂SO₄.

Step-by-step explanation:

The vapor pressure of a solution is determined by the presence of nonvolatile solutes. Nonvolatile solutes decrease the vapor pressure of the solution by impeding the evaporation of solvent molecules. The solution with the lowest vapor pressure is the one with the highest concentration of nonvolatile solute.

In this case, the solution with the lowest vapor pressure is 0.040 M (NH₄⁺)₂SO₄.