GenChem II
posted by Chem .
What mass of CsBr must be added to .500L of water to produce .4molality solution? What are mole fraction and mass percent?
Here is my work and below I will post a question about it:
1 mol CsBr = 212.81g
density of water = 1g/mL
d=mv
1=x/500
x=500g of water > solvent
.4molality = x/.5kg
x=.2mol CsBr
1 mol CsBr = 212.81g > .2mol = 42.6g
1 mol H20 = 18.016g
500g of H20 = 27.753mols H20
mole fraction = .2/27.953 = .00715
mass percent = 42.562/542.562 x 100 = 7.8%
MY QUESTION: The solution manual to my text book says that the mass of water is 500mass(solute). Didn't we already establish that the mass of water is 500g by using water's density? Thank you
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