Question

The density of 'x' M solution ('x' molar) of NaOH is 1.12 g \(mL^{-1}\). while in molality, the concentration of the solution is 3 m (3 molal). Then x is 

(Given : Molar mass of NaOH is 40 g/mol) 

(1) 3.5 

(2) 3.0 

(3) 3.8 

(4) 2.8

Answer 1

Correct option is (2) 3.0 

Molality = \(\frac {1000\times M}{1000 \times d - M \times (Mw)_{solute}}\)

\(3= \frac {1000\times x}{1000 \times 1.12 - (x \times 40)}\)

x = 3