Calculate molar concentration (molarity) of 0.9% (weight/ volume) sodium chloride (NaCl) solution.

Solution:

Molar concentration = number of moles/ volume of solution in liters

0.9% = 0.9 grams/ 100 ml solution.

0.9% = 9 grams/ 1000 ml solution = 9 g/ liter.

Number of moles = mass/ molar mass

Molar mass ( molecular weight ) of sodium chloride = 58.44 g/ mole.

Number of moles = 9 g/ (58.44 g/ mole) = 0.15 mole.

Molar concentration = 0.15 mole/ 1 liter = 0.15 M.

Related posts:
How to prepare isotonic solutions.
Isotonic solutions in pharmaceutical preparations.