Answer is: the osmotic pressure of aqueous solution of aspirin is 0.0407 atm.
m(C₉H₈O₄) = 75 mg ÷ 1000 mg/g = 0.075 g.
n(C₉H₈O₄) = 0.075 g ÷ 180.16 g/mol.
n(C₉H₈O₄) = 0.000416 mol.
c(C₉H₈O₄) = 0.000416 mol ÷ 0.250 L.
c(C₉H₈O₄) = 0.00167 M; concentration of solution.
T(C₉H₈O₄) = 25°C = 298.15 K; temperature in Kelvins.
R = 0.08206 L•atm/mol•K; universal gas constant.
π = c(C₉H₈O₄) • T(C₉H₈O₄) • R.
π = 0.00167 mol/L • 298.15 K • 0.08206 L•atm/mol•K.
π = 0.0407 atm.
