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Question 41. Determine the osmotic pressure of a solution prepared bydissolving 25 mg of K2S04 in 2L of water at 25°C, assuming that it iscompletely dissociated. |
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Answer» Mass of K2SO4, w= 25 mg= 0.025g(use 1 g= 1000 mg )Volume V= 2 literT = 25 + 273= 298 K (add 273 to convert in Kelvin)Thereaction of dissociation of K2SO4K2So4→ 2K++SO42-Number if ions produced= 2+ 1= 3So van’t Hoff factor i= 3 Use the formula of Osmotic pressureπ=i n/v RT=i w/MV RT Gas constant, R = 0.0821 L atm K-1mol-1 Molar mass of K2SO4,M= 2 × 39 + 1 × 32 + 4 × 16 = 174 g mol-1Plug the values we getπ=3×(0.025/174)×(1/2)×0.0821×298=5.27×10^-3 atm |
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