A 0.630 m aqueous solution of kbr has a total mass of 86.0 g. what masses of solute and solvent are present?

The concentration given here is in terms of molality which is moles of solute per kg of solution. Therefore, we multiply the concentration by the total mass of the solution and obtain the moles of solute. We can convert this into grams and calculate for the solvent.

0.630 mol KBr / kg solution (.086 kg solution) = 0.0542 mol KBr

0.0542 mol Kbr (119.002 g / 1 mol) = 6.4475 g KBr

Mass of solvent = 86 - 6.4475 = 79.55 g water