## Chemistry and Chemical Reactivity (9th Edition)

a) Molality: $\Delta T_f=K_fm\rightarrow m=-0.229^{\circ}C\div-1.86^{\circ}C/m=0.123\ m$ In 1 kg of the solution: Mass of solute: $4/100\times 1000\ g=40\ g$ Number of moles of solute: $0.123\ m\times 0.96\ kg =0.118\ mol$ Molar mass: $40\ g\div0.118\ mol=338.43\ g/mol$ Volume: $1000\ g\div1.014\ g/mL=986\ mL=0.986\ L$ Molarity: $0.118\ mol\div 0.986\ L=0.120\ mol/L$ b) Osmotic pressure: $\Pi=cRT=0.120\ mol/L\times 0.082\ L.atm/mol.K\times (273+25)=2.93\ atm$