Osmotic pressure of $1.5 \%$ solution of urea has been found to be 6.0 atm ant that of $3.42 \%$ sol

Question

Osmotic pressure of $1.5 \%$ solution of urea has been found to be 6.0 atm ant that of $3.42 \%$ solution of cane sugar is 2.4 atm . When 100 mL each of these two solutions are mixed, the resulting solution has an osmotic pressure of

Professor PC Thomas Classes · Answer

When equal volumes of two solutions are mixed, volume is doubled and molarity is halved. Consequently osmotic pressure is also halved. $\pi_{1}=\frac{1.5 	imes 1000 RT}{60 	imes 100}=6.0 atm$ $\pi_{2}=\frac{3.42 	imes 1000 RT}{342 	imes 100}=2.4 atm$ $\pi_{mix }=\frac{1 	imes 6.0}{2}+\frac{1 	imes 2.4}{2}=4.2 atm$