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www.GOALias.blogspot.com5Acids, Bases and SaltsWe use in our daily life a largenumber of substances suchas lemon, tamarind, commonsalt, sugar and vinegar. Do they havethe same taste? Let us recall tastes ofsome edible substances listed inTable 5.1. If you have not tasted any ofthese substances taste it now and enterthe result in Table 5.1.CAUTION1. Do not taste anything unless askedto do so.2. Do not touch anything unless askedto do so.SubstanceLemon juiceOrange juiceVinegarCurdTamarind (imli)SugarCommon saltAmlaBaking sodaGrapesUnripe mangoTable 5.1Taste (sour/bitter/any other)You find that some of thesesubstances taste sour, some taste bitter,some taste sweet and some taste salty.5.1 A5.1 ACIDSAND BASESCurd, lemon juice, orange juice andvinegar taste sour. These substancestaste sour because they contain acids.The chemical nature of suchsubstances is acidic. The word acidcomes from the Latin word acere whichmeans sour. The acids in thesesubstances are natural acids.What about baking soda? Does it alsotaste sour? If not, what is its taste? Since,it does not taste sour it means, that ithas no acids in it. It is bitter in taste. Ifyou rub its solution between fingers, itfeels soapy. Substances like these whichare bitter in taste and feel soapy ontouching are known as bases. The natureof such substances is said to be basic.If we cannot taste every substance,how do we find its nature?Special type of substances are usedto test whether a substance is acidic orbasic. These substances are known asindicators. The indicators change theircolour when added to a solutioncontaining an acidic or a basicsubstance. Turmeric, litmus, china rosepetals (Gudhal), etc., are some of thenaturally occurring indicators.