Question

What is the molarity of a solution prepared by dissolving 27.2 g of sodium chloride in enough water to prepare 500.0 ml of solution?

Answer 1

Molar mass NaCl  : 58.44 g/mol

number of moles:

n  = mass solute / molar mass

n =27.2 / 58.44

n = 0.465 moles

Volume in liters : 500.0 mL / 1000 = 0.5 L 

therefore:

Molarity  = moles solute / volume 

Molarity =  0.465 / 0.5 => 0.93 M

Answer 2

Molarity is calculated by dividing the number of moles of solute by the volume (in liters) of the solution.

Moles NaCl, n:    n  = mass /molar mass   = 27.2 g / (58.45 g/mol)
                                    n = 0.465 moles
Molarity of solution:
                          M = n / V   = (0.465 moles) / (0.50 L) = 0.93 M
Thus, the molarity of the solution is approximately 0.93 M.