QJEEM12Ch5fdd: JEE Main 2012 Chemistry - Class 11 JEEM12Ch5fdd Solution: The density of a solution prepared by dissolving 120 g of urea…

Question

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The density of a solution prepared by dissolving 120 g of urea (mol. Mass = 60 u ) in 1000g of water is 1.15 g/mL. The molarity of this solution is :

Accepted Answer

We know molarity (M) =

\frac{n o o f m o l e s o f s o l u t e}{v o l u m e o f s o l u t i o n i n l i t r e}

Moles of solute =

\frac{120}{60}

= 2

Mass of solution = 1000 + 120 = 1120 gm

Density of solution = 1.15 g/mL

∴

volume of solution =

\frac{1120}{1.15}

= 973.9 mL =

\frac{973.9}{1000}

litre = 0.9739 litre

∴

M =

\frac{2}{0.9739}

= 2.05

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