Molarity is expressed as the number of moles of solute per volume of the solution. For example, we are given a solution of 2M NaOH this describes a solution that has 2 moles of NaOH per 1 L volume of the solution. We calculate as follows:
0.115 M = n mol KBr / .55 L solution
n = 0.06325 mol KBr
mass = 0.06325 mol KBr (119 g / mol) = 7.53 g KBr
