In class VII you learnt about acids, bases and salts. You know that acids are sour to taste and turn blue litmus to red, bases are soapy to touch and turn red litmus to blue. You noticed that the person suffering from a problem of acidity, takes antacid tonic or chewing tablets.
There are many natural materials like litmus, extract of red cabbage, turmeric solution and extracts of coloured petals of some flowers contain dye molecules which are weak acids or bases. These can be used as acid- base indicators to detect the nature of the solution for acidity or basicity. In adition to the above natural acid-base indicators, there are some synthetic indicators such as methyl orange and phenolphthalein that can be used to test for acids and bases.
In this chapter you study the reactions of acids and bases. How do acids neutralize bases? Many more interesting activities that we use and see in our day-to-day life are also studied.