Question

a solution of sucrose (c12h22o11) contains 13.5g in 100 ml of the solution the density =1.05kg/L calculate the molality of the solution

Answer 1

molality = moles solute/kg solvent

getting moles solute is as simple as dividing mass of sucrose/molar mass of sucrose

to get kg solvent, we need to find out the mass of the solution, then subtract the mass of the solute.

100 mL solution ----> converting to L, we get 100/1000 = 0.1L
multiply this by the density to get kg of *solution*

then subtract the mass of the solute (13.5g, or 0.0135kg to keep units consistent). the remainder is your mass of solution in kg.

plug your quantities into molality = moles solute/kg solvent