concentration of solution is number of moles per 1 L solution. the mass of KBr added - 78 g molar mass of KBr - 119 g/mol number of moles of KBr added - 78 g / 119 g/mol = 0.655 mol final volume - 500 mL the number of moles in 500 mL - 0.655 mol therefore in 1000 mL - 0.655 mol / 500 mL x 1000 mL/L = 1.31 mol/L concentration of KBr is 1.31 M
