Acids Bases and their Applications

Acids and Bases
Learning objectives
• To understand what is meant by the terms acid, base, alkali and pH.
• To recognize the mechanism of buffer solutions.
• To see the relevance of acids and bases to body chemistry, including digestion.
• To introduce and revise the importance of amino acids and zwitterions.


Read this short story then decide what is the point.
‘I feel ghastly, my tongue is like leather and my stomach is upset. It must have been that big meal I had last night and the few drinks I had. My stomach is out of order.’
‘Then take an Alka-Seltzer or something. That helps. It is good for upset stomachs. It helps to restore the correct acidity.’

Buffers . . . we all need them. These are chemicals that manage to maintain a stable body pH. by the way they react with excess acid or alkali. Too much acid and a stomach ulcer develops; too little acid and digestion of foods is affected. Buffers keep the pH just right. Over-eating makes the stomach buffers work overtime and they can take some time to catch up after over-indulgence. The proteins and amino acids of our bodies work as part of the buffer system.
Acids
The term ‘acid’ has entered modern speech in terms such as ‘acid rain’, ‘acid parties’, ‘acid indigestion’, etc. These terms are used in conversational language but not in a scientifically correct way. In science we need to define clearly what is meant by ‘acid’. Similarly, confusion of terminology has arisen with the word ‘base’, e.g. meaning low or bottom, as in the word ‘basement’.
‘Salt’ is often used to mean common salt or sodium chloride, whereas in fact ‘salt’ is a general name used for a wide range of compounds produced when an acid reacts with an alkali.
An acid is a substance containing hydrogen atoms, some of which, when the acid is dissolved in water, produce hydrogen ions