a. A bottle of wine contains 13.5 % ethanol by volume. Calculate the concentration of ethanol in terms of mass percent. The density of ethanol (C₂H5OH) is 0.789 g/cm² and the density of wine is 0.9784 g/cm³. b. When 2.81 L of 0.0570 M Ba(OH)2 is mixed with 2.75 L of 0.0782 M Na₂SO4 a precipitate is formed. Write a balanced equation for this reaction (include the state of the reactants and products) and calculate the mass of the precipitate formed. Molar mass of BaSO4 = 233.37 g/mol.