Question

Density of $3M$ solution of $NaCl$ is $1.25g/mL$ The mass of the solvent in the solution is

• A. $1075.4g$
• B. $10.745g$
• C. $10.754g$
• D. $1074.5g$

Answer 1

Answer: (D)

$d=1\cdot 25g/mL$, conc, of solution $=3M$
$=3$ moles in one litre of the solution.
Molar mass of $NaCl=23+35\cdot 5=58\cdot 5gmo{l}^{-1}$
Volume of solution $=1L=1000mL$
Mass of solution $=d\times V$
$=1\cdot 25gm{L}^{-1}\times 1000mL$
$=1250g$
Mass of solute $(NaCl)=n\times$ molar mass
$=3\times 58\cdot 5:175\cdot 5g$
Mass of solvent
= Mass of solution $-$ mass of solute
$=1250-175.5=1074.5g$