How to prepare 1 liter of a buffer mixture of pH = 9.5 starting from HCl and 10 mmol of Na2CO3? What will the pH value be after adding to 100 ml of the buffer mixture: a) 5.10-2 mmol of NaOH? b) 5.10-2 mmol of HCl? 5.10^-2 mmol of NaOH means 5x10^-5 moles of NaOH pka of HCO3-/CO3^2- = 10,30