Respuesta :
Answer: The freezing point of solution is -0.09°C
Explanation:
To calculate the concentration of solute, we use the equation for osmotic pressure, which is:
[tex]\pi=imRT[/tex]
where,
[tex]\pi[/tex] = osmotic pressure of the solution = 120 kPa
i = Van't hoff factor = 1 (for non-electrolytes)
m = concentration of solute in terms of molality = ?
R = Gas constant = [tex]8.31\text{L kPa }mol^{-1}K^{-1}[/tex]
T = temperature of the solution = 300 K
Putting values in above equation, we get:
[tex]120kPa=1\times m\times 8.31\text{ L kPa }mol^{-1}K^{-1}\times 300K\\\\m=0.05m[/tex]
- To calculate the depression in freezing point, we use the equation:
[tex]\Delta T=i\times K_f\times m[/tex]
where,
i = Vant hoff factor = 1 (for non-electrolytes)
[tex]K_f[/tex] = molal freezing point depression constant = 1.86°C/m
m = molality of solution = 0.05 m
Putting values in above equation, we get:
[tex]\Delta T=1\times 1.86^oC/m\times 0.05m\\\\\Delta T=0.09^oC[/tex]
Depression in freezing point is defined as the difference in the freezing point of water and freezing point of solution.
- The equation used to calculate freezing point of solution is:
[tex]\Delta T=\text{freezing point of water}-\text{freezing point of solution}[/tex]
where,
[tex]\Delta T[/tex] = Depression in freezing point = 0.09 °C
Freezing point of water = 0°C
Freezing point of solution = ?
Putting values in above equation, we get:
[tex]0.09^oC=0^oC-\text{Freezing point of solution}\\\\\text{Freezing point of solution}=-0.09^oC[/tex]
Hence, the freezing point of solution is -0.09°C
