At 28.0^°C, the vapor pressure of n-propyl mercaptan, C₃H₇SH, is 175 torr, while that ofacetonitrile, CH₃CN, is 102 torr. What is the vapor pressure, at 28.0°C, of a solution made bymixing 80.0 g of C₃H₇SH and 120.0 g CH₃CN, if Raoult's Law is obeyed?Hint: Organizing the given information into moles and mole fraction of each component will help in solving this problem.

Question

Quizplus · Accepted Answer

Raoult's Law states that the vapor pressure of a solution is equal to the sum of the vapor pressures of the pure components multiplied by their mole fractions in the solution. In this case, we have:Ptotal = P(C3H7SH) + P(CH3CN)Ptotal = X(C3H7SH) * P(C3H7SH) + X(CH3CN) * P(CH3CN)where X is the mole fraction of each component.We can calculate the mole fraction of each component as follows:X(C3H7SH) = moles of C3H7SH / total molesX(C3H7SH) = 80.0 g / 76.14 g/mol / (80.0 g / 76.14 g/mol + 120.0 g / 41.05 g/mol)X(C3H7SH) = 0.533X(CH3CN) = moles of CH3CN / total molesX(CH3CN) = 120.0 g / 41.05 g/mol / (80.0 g / 76.14 g/mol + 120.0 g / 41.05 g/mol)X(CH3CN) = 0.467Now we can substitute these values into Raoult's Law to calculate the total vapor pressure:Ptotal = 0.533 * 175 torr + 0.467 * 102 torrPtotal = 131 torrTherefore, the vapor pressure of the solution at 28.0°C is 131 torr.

At 280°C, the Vapor Pressure of N-Propyl Mercaptan, C3H7SH, Is 175

At 280^°C, the Vapor Pressure of N-Propyl Mercaptan, C₃H₇SH, Is 175