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

Question

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

Answer 1

To calculate the freezing point and boiling point of the solution, we need to determine the change in freezing point and boiling point caused by the presence of the solute (sulfur) in the solvent (acetic acid). This can be done by using the molality of the solution and the cryoscopic (freezing point depression) and ebullioscopic (boiling point elevation) constants of the solvent.

First, we need to find the molality (m) of the solution. Molality is defined as the number of moles of solute per kilogram of solvent. We can calculate the molality using the following formula:

molality (m) = moles of solute / mass of solvent (in kg)

Given:
Mass of sulfur (S8) = 0.834 g
Molar mass of sulfur (S8) = 256.48 g/mol
Mass of acetic acid (HC2H3O2) = 100.0 g
Molar mass of acetic acid (HC2H3O2) = 60.05 g/mol
Freezing point depression constant (Kf) for acetic acid = 3.90 °C/m
Boiling point elevation constant (Kb) for acetic acid = 3.07 °C/m

Step 1: Calculate the moles of sulfur (S8):
moles of sulfur (S8) = mass / molar mass
moles of sulfur (S8) = 0.834 g / 256.48 g/mol

Step 2: Convert mass of solvent (acetic acid) to kg:
mass of solvent (acetic acid) = 100.0 g / 1000 = 0.100 kg

Step 3: Calculate the molality (m) of the solution:
molality (m) = moles of sulfur (S8) / mass of solvent (in kg)

Step 4: Calculate the change in freezing point (ΔTf):
ΔTf = Kf * molality

Step 5: Calculate the freezing point of the solution:
freezing point of the solution = freezing point of pure solvent - ΔTf

Step 6: Calculate the change in boiling point (ΔTb):
ΔTb = Kb * molality

Step 7: Calculate the boiling point of the solution:
boiling point of the solution = boiling point of pure solvent + ΔTb

Now, you can refer to the cryoscopic and ebullioscopic constant values from the table in your textbook to calculate the final freezing point and boiling point of the solution.