2.41 Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 litre of water at 25° C, assuming that it is completely dissociated.
When K2SO4 is dissolved in water, K+ and SO2-4K+ and SO2−4 ions are produced.
K2SO4→2K++SO2-4K2SO4→2K++SO2−4
Total number of ions produced = 3
∴i =3
Given, w = 25 mg = 0.025 g
V = 2 L
T = 25° C = (25 + 273) K = 298 K Also,
we know that:
R = 0.0821 L atm K-1mol-1
M = (2 × 39) + (1 × 32) + (4 × 16) = 174 g mol-1
Appling the following relation,
π=invRT
=iwM1vRT
=3×0.025174×12×0.0821×298
=5.27×10-3 atm
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