Q.
The density of 20% (mass/mass) aqueous KI is 1.202g/L . The molality of the solution is x . Then the value of 10x is (nearest integer)
320
165
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Answer: 15
Solution:
Weight of KI in 100g of water =20g
Weight of water in the solution =100−20=80g=0.08kg
Molar mass of KI=39+127=166gmol−1
Molality of the solution (m)=Mass of water in kgNumber of moles of KI =(0⋅08kg)(20g)/(166gmol−1) =1.506molkg−1=1.506m
By rounding off to one place, we get the molality as 1.5.