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Solutions

Question
CBSEENCH12005745

Determine the osmotic pressure of a solution prepared by dissolving 25 mg of K2SO4 in 2 litre of water at 250 C, assuming that it is completely dissociated. 

Solution
Answer:
When K2SO4 is dissolved in water , K+ and SO42- ion produced

K2SO4  2K+ + SO42-
total number of ion produced 3
therfore, i = 3
given that 

w = 25 mg = 0.025g
T = 250C + 273 = 298 K
Also  we know that 
R = 0.0821 L atm K-1 mol-1
M= (2 x39)+(1x 32)+(4x16)
Osmotic pressure, π=?
 
 V = 2L,  i = 3
π = i n2 RTV = i w RTmVπ = 3×25×10-3×0.0821×298174×2    = 5.27 × 10-3 atm.