An aqueous buffer solution contains both the zwitterion and the anionic forms of alanine. Draw the zwitterion of alanine.

Calculate the pH of a buffer solution which contains 0.700 mol dm^–3 of the zwitterion and 0.500 mol dm^–3 of the anionic form of alanine. 

Alanine pK_a = 9.87.

Penalize incorrect bond linkages or missing hydrogens once only in 8 (a) and 8 (c) (i).

[1 mark]

«pH = 9.87 + log\(\left( {\frac{{0.500}}{{0.700}}} \right)\)»

«= 9.87 – 0.146»

= 9.72

pH can be deduced by an alternative method.

[1 mark]