The density of 3 M solution of NaCl is 1.25 g mL–1 . Calculate molar

1.	The density of 3 M solution of NaCl is 1.25 g mL–1 . Calculate molarity of the solution.
Answer» M = 3 mol L^–1 Mass of NaCl in 1 litre solution = 3 × 58.5 = 175.5 g Mass of 1 L solution = 1000 × 1.25 = 1250 g (∵ Density = 1.25 g mL^–1 ) Mass of water in solution = 1250 – 175.5 = 1074.5 Molarity = \(\frac{No.\,of\,moles\,of\,solute}{Mass\,of\,solvent\,in\,kg}\) = \(\frac{3\,mol}{1.0745\,kg}\) = 2.79 m

The density of 3 M solution of NaCl is 1.25 g mL–1 . Calculate molarity of the solution.

Answer»

M = 3 mol L^–1

Mass of NaCl in 1 litre solution = 3 × 58.5 = 175.5 g

Mass of 1 L solution = 1000 × 1.25 = 1250 g

(∵ Density = 1.25 g mL^–1 )

Mass of water in solution = 1250 – 175.5

= 1074.5

Molarity = \(\frac{No.\,of\,moles\,of\,solute}{Mass\,of\,solvent\,in\,kg}\)

= \(\frac{3\,mol}{1.0745\,kg}\)

= 2.79 m