In the beginning, people would eat the food they eat, wear the clothes they wear and use the items they would use without much regard to what they really looked like. Nowadays, the first indication of quality of a product begins with how it looks; is it the right size and shape? Does it look like what it is supposed to? Is it the right colour?

If you go into a supermarket and buy washing powder, you would expect it to be white. If you opened the box and found it was yellow, chances are you wouldn’t be using it at all and may be a bit annoyed you spent your money on it.

Why should you measure the colour of acid?