4. a) A formic acid, sodium formate solution is made up by dissolving 0.2 mole of formic acid and 0.3 mole of sodium formate in 500 mL of water? What pH wil the resulting solution be at? b) If 0.5 mL of 12 M HCl is added to this buffer solution what will be the resulting pH? c) If 0.0125 mole of NaOH is added to the original solution in part a) what will be the resulting pH? 5. a) A 0.05 M NH; solution has 0.1 mole of powdered NH4Cl added to it. What will be the resulting PH? b) 200 mL of 0.1 M NH, is added to 200 mL of 0.25 M NH4C1. What is the pH of the resulting solution? c) 500 mL of 1 M citric acid has 0.1 mole of sodium citrate added to it. What is the resulting pH? (K= 6.58 104) 6. What ratio of molar concentrations of NH4Cl and NHz would buffer a solution at pH 9.25