<u>Answer:</u> The Van't Hoff factor for KCl is 1.74
<u>Explanation:</u>
We are given:
Molality of solution = 1 m
This means that 1 mole of a solute is present in 1 kg of solvent (water) or 1000 grams of 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:
Moles of solute = 1 moles
Total moles = [1 + 55.56] = 56.56 moles
Putting values in above equation, we get:
The equation used to calculate relative lowering of vapor pressure follows:
where,
= relative lowering in vapor pressure = 0.734 mmHg
i = Van't Hoff factor = ?
= mole fraction of solute = 0.0177
= vapor pressure of pure water = 23.76 torr
Putting values in above equation, we get:
Hence, the Van't Hoff factor for KCl is 1.74