Describe how you would prepare a phosphate buffer with a pH of 7 . 4 0 . You are provided with Phosphoric Acid ( pKa = 2.1 2 ) , sodium dihydrogen phosphate ( pKa 7.2 1 ), and disodium hydrogen phosphate ( pka 1 2.3 2 ). Write the appropriate equilibrium buffer reaction and calculate how many moles of conjugate acid and base you would need to add to water to make 1 . 0 0 L buffer solution. The determine how many grams of each you would need to add to 1 . 0 0 L of DI water.