Question

An organic substance (M = 169 gram mol^-1) is dissolved in 2000 cm³ of water. Its osmotic pressure at 12°C was found to be 0.54 atm. If R = 0.0821 L atm K^-1 mol^-1, calculate the mass of the solute.

Answer 1

Given : 

M = 169 g mol^-1

V = 200 cm³ = 0.2 dm³ 

T = 273 + 125 = 285 K 

π = 0.54 atm 

R = 0.0821 L atm K^-1 mol^-1; 

W = ?

∴ Mass of solute = 0.78 g