1.1. This question is about buffer solutions

Calculate the pH of a buffer solution made by dissolving 0.275 g of benzoic acid (K_a  = 6.3 x 10^-5 mol dm^-3) and 0.525 g of sodium benzoate in 250 cm³ of water. Give your answer to 2 decimal places and show your working.

pH = .................

1.2. Calculate the pH of a buffer solution made by mixing together 130 cm³ of 0.2 mol dm^-3 ethanoic acid (K_a = 1.74 x 10^-5 mol dm^-3) and 85 cm³ of 0.45 mol dm^-3 sodium ethanoate. Give your answer to 2 decimal places and show your working.

pH = .....................

1.3. Calculate the new pH of the buffer solution given in part (b) if 1.00 cm³ of 1.00 mol dm^-3 sodium hydroxide is added. Give your answer to two decimal places and show your working. 

Comment on the pH value after the addition of sodium hydroxide.

pH = ...................

1.4. Write two equations for the separate addition of a small volume of base and acid to the buffer solution given in part (b).

equation 1 ....................................................................................

equation 2 .....................................................................................