Test acid and bases using natural indicators

 Test acid and bases using natural indicators 

Test acid and bases using natural indicators How do we determine whether the substance is acidic or basic? It is not possible to taste every substance to determine the same, so the scientists have developed some substance called indicators for this purpose. Indicators change in colour when brought in contact with acidic or basic substance. Through experiment we will learn about some naturally occurring indicators like (a) China rose petal (b) Turmeric (c) Litmus paper (a) China rose petal as indictor First we need to prepare the indicator. Take some china rose petals and place them in a beaker. Add some Luke warm water and mix it. After some time you will observe the water becoming coloured. The indicator is now ready to use. Now take samples to test for acid base or neutral solution. Take samples of dilute hydrochloric acid, lemon juice, sodium hydroxide solution and soap solution. Add the china rose indicator to each solution and note your observation. We observe that the china rose indicator turns acidic solution to dark pink and basic solution to green. Soluions of Hydrochloric acid and Lime water will turn to pink colour and solutions of hydroxide solution and soap solution will turn into green colour. (b) Turmeric as indicator In this experiment we test acidic and basic solution using turmeric as natural indicator. Take samples of Lemon juice which is acidic and soap solution which is basic. Add few drops of turmeric to each solution. Did you observe the change in colour? Turmeric is a indicator which changes colour only when added to base solution. So, here in this experiment, adding turmeric to lemon juice will have no effect n change in colour, while soap solution changes its colour to red orange. (c ) Litmus as indicator Litmus is a water soluble mixture of different dyes extracted from lichens. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test substance for acidity. Litmus has purple colour in distilled water. When added to acidic solution it turns red. When added to basic solution it turns blue. Litmus paper are the most commonly used indicators. It is available in the form of solution or strips of paper blue and red in colour. Take samples of lime water, tap water, soap solution and salt solution. Put few drops of lime water on blue and red litmus paper. Observation: Blue litmus turn red as lime is aidic in nature. Put few drops of tap water on blue and red litmus paper. Observation: No change in colour in red or blue litmus paper. This means tap water is neutral. Put few drops of soap solution on blue and red litmus paper. Observation: Red litmus turns blue as soap solution is basic in nature. Put few drops of salt solution on blue and red litmus paper. Observation: No change in colour in red or blue litmus paper. This means salt solution is neutral. Put few drops of vinegar on blue and red litmus paper. Observation: Blue litmus turns red as vinegar in acidic nature Conclusion: An acid turns blue litmus red and a base turns red litmus blue. There is no change in colour for neutral solution.