What is the freezing point of a solution that contains 10.0 g of glucose (C6H12O6) in 100 g of H2O? Kf for water is 1.86oC/m
mols glucose = g/molar mass
Solve for mols.
m = mols/kg solvent
Solve for m
delta T = Kf*m
Solve for dT and subract from zero C.
To determine the freezing point of a solution, you can use the formula:
ΔT = Kf * molality
Where:
ΔT is the change in freezing point
Kf is the freezing point depression constant
molality is the molal concentration of the solution
To find the molality, you need to calculate the moles of solute (glucose) and the mass of the solvent (water).
First, calculate the moles of glucose:
Moles = mass / molar mass
The molar mass of glucose (C6H12O6) is:
6(12.01 g/mol) + 12(1.01 g/mol) + 6(16.00 g/mol) = 180.18 g/mol
Moles = 10.0 g / 180.18 g/mol = 0.0555 mol
Next, calculate the mass of the solvent (water):
Mass of water = 100 g
Now, calculate the molality:
Molality = moles of solute / mass of solvent (in kg)
Mass of solvent (in kg) = 100 g / 1000 = 0.1 kg
Molality = 0.0555 mol / 0.1 kg = 0.555 mol/kg
Finally, substitute the values into the formula:
ΔT = Kf * molality
ΔT = 1.86 oC/m * 0.555 mol/kg = 1.0323 oC
Therefore, the freezing point of the solution is lowered by 1.0323 oC.
To find the freezing point of the solution, we can use the formula:
ΔTf = Kf * m
Where:
- ΔTf is the change in freezing point
- Kf is the freezing point depression constant for the solvent
- m is the molality of the solute
First, we need to calculate the molality of the solute (glucose):
Molar mass of glucose (C6H12O6) = 180.16 g/mol
Number of moles of glucose = Mass / Molar mass
Number of moles of glucose = 10.0 g / 180.16 g/mol
Next, we need to calculate the molality (moles of solute per kilogram of solvent) of the solution. Since we have 100 g of water, which is equivalent to 0.1 kg:
Molality (m) = Moles of solute / Mass of solvent in kg
Molality = (10.0 g / 180.16 g/mol) / 0.1 kg
Now we can substitute the values into the formula:
ΔTf = 1.86oC/m * (10.0 g / 180.16 g/mol) / 0.1 kg
After performing the calculations, we can determine the freezing point depression (ΔTf) of the solution. Since pure water freezes at 0oC, the freezing point of the solution can be found by subtracting the value of ΔTf from the freezing point of water.