Mass percentage of ethanol is 13%. Density of ethanol is 0.978 g/mL. I mL of ethanol solution weighs 0.978 therefore 1 L of solution will weigh 978 g. Since mass percentage is 13%, the weight of ethanol in 1 L of solution will be - 978 g x 13 % = 127.14 g molar mass of ethanol is 46 g/mol Therefore number of ethanol moles in 1 L - 127.14 g/ 46 g/mol = 2.76 mol Molarity of ethanol solution - 2.76 mol/L = 2.76 M
