Question
If you dissolve 29.25 g of sodium chloride in 250 g of H2O. What would be the freezing point?
Kfp- -1.86 degrees C/molal
I know the formula is K times molality.
I am taking -1.86(2.00) and getting -3.72 degrees Celsius, when the answer is -7.44 degrees. What am I doing wrong?
Kfp- -1.86 degrees C/molal
I know the formula is K times molality.
I am taking -1.86(2.00) and getting -3.72 degrees Celsius, when the answer is -7.44 degrees. What am I doing wrong?
Answers
DrBob222
delta T = i*Kf*m
Your problem is you have half the answer which means you aren't using i = van't Hoff factor.
How many moles NaCl in 29.25g? That will be moles = grams/molar mass. Solve for moles.
What is molality?
That will be m = moles/kg solvent
Solve for m
What is i?
i = 2 for Nacl.
Substitute into the formula.
Your problem is you have half the answer which means you aren't using i = van't Hoff factor.
How many moles NaCl in 29.25g? That will be moles = grams/molar mass. Solve for moles.
What is molality?
That will be m = moles/kg solvent
Solve for m
What is i?
i = 2 for Nacl.
Substitute into the formula.