Buffer Solutions

 

1.  4 mol of sodium ethanoate and 3 mol of ethanoic acid are dissolved in a large volume of water.  Given that the ionisation constant of the acid is  1.78 x 10-5  mol dm-3, calculate the pH of this buffer solution.

(4.87)

 

2.  In order to prepare a buffer solution of pH = 5.0, calculate the molar ratio of ethanoic acid, acid ionisation constant = 1.75 x 10-5 mol dm-3 at 298K, to sodium ethanoate in solution.

(4/7)

 

3.  Calculate the number of moles of sodium ethanoate which must be present in 500 cm3 of 0.100M ethanoic acid (acid ionisation constant = 1.8 x 10-5 mol dm-3) in order to give a solution  of pH = 4.44.

(0.025)?

 

4.  Calculate the pH of a solution produced by mixing 50 cm3 of 0.1M ethanoic acid with 150 cm3 of potassium ethanoate solution.

(The acidity constant of ethanoic acid at room temperature is 1.7 x 10-5 mol dm-3).

(5.37)