Q. Density of 3 M NaCl solution is 1.25 g/mL. The molality of the solution is :
A) 1.79 m
B) 2.79 m
C) 2 m
D) 3 m
Explanation
[Solution by Dr. Abubacker] In 1 L of solution: mass $=1250$ g; NaCl $=3\times58.5=175.5$ g; solvent $=1250-175.5=1074.5$ g $=1.0745$ kg. Molality $=\frac3{1.0745}=2.79$ m. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.