**Learning Goal:** Precipitation is the formation of an insoluble substance. For the equation \( AB(s) \rightleftharpoons A^+(aq) + B^−(aq) \), precipitation represents a shift to the left and the production of a solid. From Le Châtelier's principle, we know that when the product of the concentrations of \( A^+ \) and \( B^− \) gets above a certain level, the reaction will respond by shifting left to decrease the concentrations of \( A^+ \) and \( B^− \). This critical level, \( K_{sp} \), is a constant at a certain temperature. In this case, \( Q = [A^+][B^−] \), where \( Q \) is the ion product. When \( Q > K_{sp} \), precipitation occurs until \( Q \) is equal to \( K_{sp} \). When \( Q \leq K_{sp} \), a precipitate does not form.

**Part A:** If 0.180 mol of a nonvolatile nonelectrolyte is dissolved in 3.30 mol of water, what is the vapor pressure \( P_{H_2O} \) of the resulting solution? The vapor pressure of pure water is 23.8 torr at 25°C. Express your answer with the appropriate units.

**Part B:** A solution is composed of 1.10 mol cyclohexane (\( P^\circ_{\text{cy}} = 97.6 \) torr) and 2.50 mol acetone (\( P^\circ_{\text{ac}} = 229.5 \) torr). What is the total vapor pressure \( P_{\text{total}} \) above this solution?

**Part C:** As you saw in Part B, the vapor above the cyclohexane-acetone solution is composed of both cyclohexane vapor and acetone vapor. What mole fraction of the vapor above the solution, \( X_{\text{cy}}(\text{vapor}) \), is cyclohexane?