a solution of 0.2113 g of water dissolv ed in 25g of a solvent freezes at 11.5 degrees celcius below the freezing point of the solvent. what is the Kf for the solvent?
A)0.735
B)1.36
c)5.39
D)24.5
Help!!!
delta T = Kf*molality
Calculate molality = #mols solute/kg solvent, plug into the first equation and calculate Kf.
Post your work if you need further assistance.
To find the Kf (freezing point depression constant) for the solvent, we can use the formula:
delta T = Kf * molality
Given that the solution with 0.2113 g of water dissolved in 25 g of solvent freezes at 11.5 degrees Celsius below the freezing point of the solvent, we need to calculate the molality of the solution first.
Molality (m) is defined as the number of moles of solute per kilogram of solvent. To find the mole of water, we can use its molar mass, which is 18.015 g/mol.
Moles of water = mass of water / molar mass of water
Moles of water = 0.2113 g / 18.015 g/mol
Next, we need to find the mass of the solvent in kg:
Mass of solvent = 25 g / 1000 (to convert to kg)
Now, we can calculate the molality:
Molality (m) = Moles of solute / Mass of solvent in kg
Now, substitute the molality and the change in temperature (delta T) into the equation and solve for Kf:
11.5 degrees Celsius = Kf * molality
Finally, rearrange the equation to solve for Kf:
Kf = 11.5 degrees Celsius / molality
Once you have calculated the molality, divide the change in temperature (11.5 degrees Celsius) by the molality to determine the Kf value.
After obtaining the Kf value, compare it to the options given (A, B, C, D) and select the correct option.
If you need further assistance or have any more questions, please let me know.