Question

Molarity and molality of a solution of an liquid ( molecular mass =50)in aqueous solution is 9 and 10 respectively .What is the density of solution

Answer 1

Molarity = moles of solute/volume of soln. in ltres.

      9 mol/litre     = (w/50)/(m/d)...................................(1)

10 molality means 10 moles are present in 1 kg water.

molar mass = 500 gm is present in 100 gm water. 

mass of solution = 1500 gm.

Volume = 9M/10mol and volume  = 1.1111 l

density comes to =  1500/1111 = 1.350 g/l

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