1.1. This question is about buffers.

i) Explain the term basic buffer solution.

ii) Suggest why buffers are used in the cosmetics industry.

1.2. When we exercise, chemical changes occur which can cause our blood pH to drop. If the pH drops below 7.4 a condition called acidosis occurs. This can be very dangerous as many chemical reactions involve proteins which work at pH 7.4. The most important buffer for maintaining acid-base balance in the blood is the carbonic acid, H₂CO₃, hydrogencarbonate, HCO₃^- buffer.

i) Write a balanced equation to show the dissociation of carbonic acid, acting as a buffer solution. 

ii) Explain how the carbonic acid-hydrogencarbonate buffer maintains blood pH at 7.4 when we exercise. Use your answer to part (i).

1.3. Much of the atmospheric carbon dioxide we produce is absorbed by dissolving into the oceans, forming carbonic acid. An equilibrium is set up within the oceans using the same buffer solution as in the body, described in part (b).

In this buffer solution there is an almost unlimited amount of hydrogen carbonate ions and the carbonic acid available has a high concentration.

Using your answer to (b) part (i), suggest the changes which would lead to more CO₂ dissolving into the oceans. Explain your answer.

1.4. When we exercise, lactic acid CH₃CH(OH)COOH, may be produced by anaerobic exercise, if there is insufficient oxygen reaching the muscles.

The concentration of lactic acid is approximately 0.01 mol dm^-3 in the body directly after exercise.

The dissociation constant, K_a for lactic acid is 1.288 x 10^-4 mol dm^-3.

Give the expression for K_a and calculate the pH of lactic acid.