<u>Answer:</u> The total pressure above the solution at 30°C is 45.29 mmHg
<u>Explanation:</u>
We are given:
Molality of methanol = 6.0 m
This means that 6.0 moles of methanol present in 1 kg or 1000 g of pure water
To calculate the number of moles, we use the equation:
Given mass of water = 1000 g
Molar mass of water = 18 g/mol
Putting values in above equation, we get:
Mole fraction of a substance is given by:
To calculate the total pressure, we use the equation given by Dalton and Raoults, which is:
where,
= total vapor pressure = ?
We are given:
Mole fraction of methanol = 0.0975
Mole fraction of water = 0.9025
Vapor pressure of methanol = 170.0 mmHg
Vapor pressure of water = 31.82 mmHg
Putting values in above equation, we get:
Hence, the total pressure above the solution at 30°C is 45.29 mmHg