ppm in ionic...........

IIT JEE 2015 Sample Questions › Physical Chemistry questions › ppm in ionic...........

A particular water sample has 131ppm CaSO4.What fraction of water
must be evaporated in a container before solid CaSO4 begins to deposit.Ksp of CaSO4=9*10-6

#Chemistry #Physical Chemistry

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5 Answers

msp ·2009-01-24 22:21:16

i am getting 131/140

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gagar.iitk ·2009-01-24 22:26:36

fraction of water remain ==131/408
=0.321

fraction of water should be evaporated==1-0.321==0.679

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msp ·2009-01-24 22:33:00

can u give the soln

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gagar.iitk ·2009-01-24 22:43:26

moles of CASO4 in the remain soln can be calculated with the help of Ksp given ==3*10^-3
moles of CASO4 in 10⁶ ml of wateris 131/136
if x ml of water is remain after evaporation then then molarity of CASO4 in the soln is 131000/136x==3*10^-3
from here x ==131*10⁶/408 so the fraction evaporated is

1- (131/408)==1-0.321==0.679