Question

Calculate osmotic pressure of a solution (write only integer part) obtained on mixing $100$ mL of $3.4\%$ (mass/vol) solution of urea (molar mass $60$) and $50$ mL of $1.6\%$ (mass/vol) solution of cane sugar (molar mass $342$) at ${27}^{o}C$.

Answer 1

The number of moles of urea present $=100mL\times \frac{3.4g}{100mL}\times \frac{1mol}{60g}=0.0566mol$.
The number of moles of sucrose present $=50mL\times \frac{1.6g}{100mL}\times \frac{1mol}{342g}=0.002339mol$.
Total number of moles $n=0.0566mol+0.002339mol=0.0589mol$
Total molar concentration is $\frac{0.0589mol}{100mL+50mL}\times \frac{1000mL}{1L}=0.3929M$
The osmotic pressure is $\Pi =CRT=0.3929M\times 0.08206Latm-mol/K\times 300.15K=9.704atm$.