There are a number of ways to express concentration of a solution. This includes molarity. Molarity is expressed as the number of moles of solute per volume of the solution. The concentration of the solution is calculated as follows:
Molarity = 0.74 g (1 mol / 74. 55 g) / 500mL (1 L / 1000 mL)
Molarity = 0.02 M