Calculate the freezing point of 1molar aqueous solution (density =1.04g) of kcl (kf for water =1.86)K=39,cl=35.5
Convert M to m, then
delta T = Kf*m
Where is the answer????????
To calculate the freezing point of a solution, we need to use the equation for freezing point depression:
ΔTf = Kf * m
Where:
- ΔTf is the freezing point depression (the difference between the freezing point of the pure solvent and the freezing point of the solution).
- Kf is the cryoscopic constant (the molal freezing point depression constant) for the solvent. In this case, Kf is given as 1.86 ºC/m for water.
- m is the molality of the solute, which is the number of moles of solute per kilogram of solvent.
To find the molality (m) of KCl in the solution, we need to determine the number of moles of KCl dissolved and the mass (in kg) of water:
1. Calculate the number of moles of KCl:
- Molar mass of KCl = 39 + 35.5 = 74.5 g/mol
- Number of moles of KCl = 1 mol
2. Calculate the mass (in kg) of water:
- Density of the solution = 1.04 g/mL
- Volume of 1 mole of water = 18 mL
- Mass of 1 mole of water = 18 g
- Mass of water in the solution = Volume of solution * Density of solution
- Mass of water in the solution = 1000 mL * 1.04 g/mL = 1040 g
- Mass of water in the solution = 1040 g / 1000 = 1.04 kg
3. Calculate the molality (m):
- m = moles of solute / mass of solvent (in kg)
- m = 1 mol / 1.04 kg
- m = 0.962 mol/kg
Now we can substitute the values into our equation for freezing point depression:
ΔTf = Kf * m
ΔTf = 1.86 ºC/m * 0.962 mol/kg
ΔTf = 1.78932 ºC
The freezing point depression (ΔTf) is 1.78932 ºC. To find the freezing point of the solution, we subtract the freezing point depression from the freezing point of the pure solvent (water).
Freezing point of pure solvent (water) = 0 ºC
Freezing point of solution = 0 ºC - 1.78932 ºC = -1.78932 ºC
Therefore, the freezing point of the 1 molar aqueous solution of KCl is approximately -1.78932 ºC.