12. A solution contains 4.08 g of chloroform 1CHCl32 and 9.29 g of acetone 1CH3COCH32. The vapor pressures at 35 °C of pure chloroform and pure acetone are 295 torr and 332 torr, respectively. Assuming ideal behavior, calculate the vapor pressure above the solution. (LO 13.12) (a) 256 torr (b) 314 torr (c) 325 torr (d) 462 torr

Verified step by step guidance

1. Calculate the moles of chloroform (CHCl_3) using its molar mass.
2. Calculate the moles of acetone (CH_3COCH_3) using its molar mass.
3. Determine the mole fraction of chloroform by dividing the moles of chloroform by the total moles of both substances.
4. Determine the mole fraction of acetone by dividing the moles of acetone by the total moles of both substances.
5. Use Raoult's Law to calculate the total vapor pressure: P_total = (X_chloroform * P_chloroform) + (X_acetone * P_acetone), where X is the mole fraction and P is the vapor pressure of the pure component.

Key Concepts

Raoult's Law

Raoult's Law states that the vapor pressure of a solvent in a solution is directly proportional to the mole fraction of the solvent in the solution. This principle is essential for calculating the vapor pressure of a solution, as it allows us to determine how the presence of a solute affects the overall vapor pressure compared to that of the pure solvent.

Mole Fraction

Mole fraction is a way of expressing the concentration of a component in a mixture, defined as the number of moles of that component divided by the total number of moles of all components in the mixture. In this problem, calculating the mole fractions of chloroform and acetone is crucial for applying Raoult's Law to find the vapor pressure of the solution.

Ideal Solution Behavior

An ideal solution is one where the interactions between different molecules are similar to those between like molecules, leading to predictable behavior according to Raoult's Law. This assumption simplifies calculations, as it allows us to use the pure component vapor pressures and mole fractions to determine the vapor pressure of the solution without accounting for deviations due to intermolecular forces.