Chapter 13 Solutions and Their Behavior - Study Questions - Page 505e: 90

See the answer below.

Osmotic pressure: $\Pi=cRT\rightarrow c=(539/760)atm\div(0.082\ atm.L/mol.K\times 298\ K)=0.029\ mol/L$ Total number of moles of solutes: $0.029\ mol/L\times 0.1\ L=0.0029\ mol$ $x\ g/369.41\ g/mol+(1.00-x)\ g/342.30\ g/mol=0.0029\ mol\rightarrow x= 0.089\ g$ Heroin weight percent $0.089/1.00\times100\%=8.9\%$ Lactose weight percent: $100-8.9=91.1\%$