Buffer Questions
1. Calculate the pH of a buffered solution made up of 0.015 M sodium acetate and 1 L of 0.10 M acetic acid.
2. A nutrition scientist needed an aqueous buffer for a pH of 3.90.  Would formic acid andit's salt sodium formate, make a good pair for this purpose?  If so, what mole ratio of the anion of this salt, CHO2-1, to the acid, HCHO2, is needed?
3. A buffer solution was prepareed by dissolving 2.5 grams of NH4Cl in 125 mL of 0.24 M ammonia solution.  At what pH will this solution serve as a buffer?
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 NH3 solution has 0.1 mole of powdered NH4Cl added to it.  What will be the resulting pH?

b)  200 mL of  0.1 M NH3 is added to 200 mL of 0.25 M NH4Cl.  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?
6. Barbituric acid is an extremely powerful sedative.  Most drug manufacturers use equal amounts, grams that is, of barbuturic acid and sodium barbiturate in their pills.   An average 'Percodan' tm, a barbiturate based pill, is 70% bulk starch and sugar.  If the average pill is 0.5 g in mass what will be the pH of the solution made by dissolving the above pill in 50 mL of water?
7. A solution of pH = 7.0 is required for an experiment.  You decide to use 100 g of sodium dihydrogen phosphate (NaH2PO4), in 1 L of water.  How much sodium monohydrogen phosphate, (Na2HPO4) is needed in grams to achieve this pH?

            Answers