- #1
pari786
- 29
- 0
Assume that the density of water is 1.00 g/ml . Calculate the quantity of KBr that would need to be added to lower the freezing point of 535 ml of water by 1.40 degree celsius:
What I'm trying to do is the following:
Step 1:
Tf = Kf . m
I took Tf = 1.4
Kf = 1.86
and found the molality as 0.75
Step 2:
then I used the molality equation which is
molality = moles solute/kg solvent
molality = 0.75
kg solvent = 0.535 kg
and got the no. of moles as 119 g/mol
Step 3
no. of moles = mass /molar mass and
got 47.6 g for mass
but the answer is still wrong ... I don't know where I'm making mistake. It's an online assignment so I don't know what the answer should be. But please guys help me and check if I'm doing everything right.
What I'm trying to do is the following:
Step 1:
Tf = Kf . m
I took Tf = 1.4
Kf = 1.86
and found the molality as 0.75
Step 2:
then I used the molality equation which is
molality = moles solute/kg solvent
molality = 0.75
kg solvent = 0.535 kg
and got the no. of moles as 119 g/mol
Step 3
no. of moles = mass /molar mass and
got 47.6 g for mass
but the answer is still wrong ... I don't know where I'm making mistake. It's an online assignment so I don't know what the answer should be. But please guys help me and check if I'm doing everything right.