Question

What mass of cesium bromine must be added to a 0.500 liter of water (d=1.00 g/ml) to produce a 0.981m solution? what are the mole fraction and mass percent of CsBr?

Answer 1

m = mols solute/kg solvent
You know m and kg solvent; solve for mols solute.

Then mols solute = grams/molar mass
You know mols solute and molar mass, solve for grams.

Answer 2

For mole fraction, X CsBr.
mols CsBr = from the problem
mols H2O from the problem = grams/molar mass
Then X CsBr = mols CsBr/total mols.

mass % CsBr is grams CsBr/100 g solution.