Determine the vapor pressure of a solution at 25°c that contains 76.6 g of glucose (c6h12o6) in 250.0 ml of water. the vapor pressure of pure water at 25°c is 23.8 torr.70.8 torr7.29 torr72.9 torr22.9 torr23.1 torr

The vapor pressure of solution is 23.1 torr

Explanation:

To calculate the mass of water, we use the equation:

Density of water = 1 g/mL

Volume of water = 250.0 mL

Putting values in above equation, we get:

To calculate the number of moles, we use the equation:

     .....(1)

Given mass of glucose = 76.6 g

Molar mass of glucose = 180.2 g/mol

Putting values in equation 1, we get:

Given mass of water = 250 g

Molar mass of water = 18 g/mol

Putting values in equation 1, we get:

Mole fraction of a substance is given by:

Mole fraction of glucose,

As, the relative lowering of vapor pressure is directly proportional to the amount of dissolved solute.

The equation used to calculate relative lowering of vapor pressure follows:

where,

= relative lowering in vapor pressure

i = Van't Hoff factor = 1 (for non electrolytes)

= mole fraction of solute = 0.030

= vapor pressure of pure water = 23.8 torr

= vapor pressure of solution = ?

Putting values in above equation, we get:

Hence, the vapor pressure of solution is 23.1 torr

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