1. What is the vapor pressure at 25°C of a solution of 1.20g of nephtalene C10H8 in 25.6g of benzone C6H6? The vapor pressure of pure benzene at 23°C is 86.0mmHg the vapor pressure of naphthalene can be neglected. Calculate the vapor pressure lowering of the solution.

2. A solution was prepared by dissolving 0.834g of sulfur, S8 in 100.0g of acetic acid HC2H3O2. Calculate the freezing point and the boiling point of the solution.

To answer these questions, we need to understand the concepts of vapor pressure lowering and boiling point elevation/freezing point depression.

Let's start with question 1:

1. What is the vapor pressure at 25°C of a solution of 1.20g of naphthalene (C10H8) in 25.6g of benzene (C6H6)? The vapor pressure of pure benzene at 23°C is 86.0mmHg, and the vapor pressure of naphthalene can be neglected. Calculate the vapor pressure lowering of the solution.

To calculate the vapor pressure lowering, we need to use Raoult's Law. According to Raoult's Law, the vapor pressure of a solution is directly proportional to the mole fraction of each component in the solution. In this case, we need to find the mole fraction of benzene in the solution.

Step 1: Calculate the moles of benzene:
Moles of benzene = mass of benzene / molar mass of benzene
Molar mass of benzene (C6H6) = (12.01 * 6) + (1.01 * 6) = 78.11 g/mol
Moles of benzene = 25.6g / 78.11 g/mol

Step 2: Calculate the mole fraction of benzene:
Mole fraction of benzene = Moles of benzene / (Moles of benzene + Moles of naphthalene)

Step 3: Calculate the vapor pressure of the solution using Raoult's Law:
Vapor pressure of solution = mole fraction of benzene * vapor pressure of pure benzene

Now, let's move on to question 2:

2. A solution was prepared by dissolving 0.834g of sulfur (S8) in 100.0g of acetic acid (HC2H3O2). Calculate the freezing point and boiling point of the solution.

To calculate the freezing and boiling points of a solution, we need to use the concepts of freezing point depression and boiling point elevation.

Freezing point depression: The freezing point of a solution is lower than that of the pure solvent due to the presence of solute particles, which disrupt the solvent's crystal lattice.

Boiling point elevation: The boiling point of a solution is higher than that of the pure solvent because the solute particles increase the vapor pressure of the solution.

To calculate the freezing and boiling points, we need to use the following formulas:

Freezing point depression:
ΔTF = KF * m

Boiling point elevation:
ΔTB = KB * m

where:
ΔTF is the freezing point depression or change in freezing point
ΔTB is the boiling point elevation or change in boiling point
KF is the molal freezing point depression constant specific to the solvent
KB is the molal boiling point elevation constant specific to the solvent
m is the molality of the solution (moles of solute per kg of solvent)

Step 1: Calculate the moles of sulfur:
Moles of sulfur (S8) = mass of sulfur / molar mass of sulfur
Molar mass of sulfur (S8) = 32.06 g/mol
Moles of sulfur = 0.834g / 32.06 g/mol

Step 2: Calculate the molality of the solution:
Molality (m) = Moles of solute / Mass of solvent (in kg)
Mass of acetic acid (HC2H3O2) = 100.0g = 0.1kg
Molality (m) = Moles of sulfur / 0.1kg

Step 3: Calculate the freezing point depression and boiling point elevation:
ΔTF = KF * m
ΔTB = KB * m

KF and KB are specific constants depending on the solvent. You need to look up the values for acetic acid to substitute in these equations.

Calculating these values will give you the change in freezing point and change in boiling point compared to the pure solvent.

Remember, to get the actual freezing point and boiling point, you need to add or subtract the change from the normal freezing point and boiling point of the pure solvent.

I hope this clarifies the process of solving these problems. Let me know if you need further assistance!

I answered this for you at your first post quite some time ago.