What is the molality of a solution composed of 25ml og toluene C6H5CH3 ( density=0.866g/ml) in 75 ml of benzene ( density=0.879g/ml)

Answer 1

For toluene (the solute):
mass = volume x density. Substitute and solve for mass. Then mols = mass toluene/molar mass toluene.

For benzene:
mass = volume x density. Substitute and solve for mass benzene.
Convert mass in g benzene to kg benzene (the solvent).
Then m = mols solute/kg solvent.