The density of 3 M solution of sodium chloride is 1.252 ~g ~mL^ -1 . The molality of the solution will be : (. molar mass, .NaCl=585 ~g ~mol^ -1 )

Correct answer: C. 2.79 ~m The relation between molarity (M) and molality (m) is d=M((1)/(m)+ M_2 1000 ), M_2= Mol. mass of solute On putting value 1.252=3 ((1)/(m)+(58.5)/(1000)) on solving m=2.79

JEE Main 201322 AprilOnline

Exam: JEE Main
Year: 2013
Date: 22 April
Mode: Online
Subject: Chemistry
Chapter: Some Basic Concepts of Chemistry

JEE Main 2013 · 22 April · Online · Chemistry · Some Basic Concepts of Chemistry

The density of 3 M solution of sodium chloride is 1.252 ~g ~mL^ -1...

The density of

3 \mathrm{M}

solution of sodium chloride is

1.252 \mathrm{~g} \mathrm{~mL}^{-1}

. The molality of the solution will be :

\left(\right.

molar mass,

\left.\mathrm{NaCl}=585 \mathrm{~g} \mathrm{~mol}^{-1}\right)

Options

A $260 \mathrm{~m}$
B $2.18 \mathrm{~m}$
C $2.79 \mathrm{~m}$
D $3.00 \mathrm{~m}$

Correct answer

C. $2.79 \mathrm{~m}$

Step-by-step solution

The relation between molarity (M) and molality

(m)

d=\mathrm{M}\left(\frac{1}{m}+\frac{\mathrm{M}_2}{1000}\right), \mathrm{M}_2=

Mol. mass of solute On putting value 1.252=3

\left(\frac{1}{m}+\frac{58.5}{1000}\right)

on solving

m=2.79

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