Question

Calculate the vapor pressure of water above a solution prepared by dissolving 29.0 g of glycerin (C3H8O3) in 120 g of water at 343 K.

Answer 1

The vapor pressure is 223.28 mmHg

Step-by-step explanation:

Step 1: Data given

Mass of glycerin = 29.0 grams

Mass of water = 120.0 grams

Molar mas glycerin = 92.09 g/mol

Molar mass water = 18.02 g/mol

Temperature = 343 K

The vapor pressure for 343 K is 233.7 mmHg

Step 2: Calculate moles glycerin

Moles glycerin = mass glycerin / molar mass glycerin

Moles glycerin = 29.00 grams / 92.09 g/mol

Moles glycerin = 0.315 moles

Step 3: Calculate moles water

Moles water = 120.0 grams / 18.02 g/mol

Moles water = 6.66 moles

Step 4: Calculate total moles

Total moles = 0.315 moles + 6.66 moles = 6.975 moles

Step 5: Calculate mol fraction H2O:

Mol fraction H2O = 6.66 moles / 6.975 moles = 0.955

Step 6: Calculate vapor pressure

Vapor pressure = mol fraction H2O * Vapor pressure H2O ( at 343 K)

Vapor pressure = 0.955 * 233.8 mmHg

Vapor pressure = 223.28 mmHg

The vapor pressure is 223.28 mmHg