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Solutions

Question
CBSEENCH12005744

Determine the amount of CaCl(i = 2.47) dissolved in 2.5 litre of water such that its osmotic pressure is 0.75 atm at 270C.

Solution
Answer;
π = inRTVπ = iWRTMV     where n = w/mw = πMViRT

CaCl
2 → Ca2+ + 2Cl

π = 0.75 atm


T = 273 + 27 = 300 K,
M = 1 x 40 + 2x 35.5 = 111g mol-1
V = 2.5 L
i = 2.47
       osmatic pressure, π = i n2 RTV 

                  w= πMViRTtherefore w= 0.75×111×2.52.47×0.082×300  = 3.42 g
 

amount of calcium chloride dissolved is 3.42g