User:Dilshadivakaran/sandbox

INDICATORS
Indicators are those substances which used to check whether a substance is acid or base. When indicators are added to acid or base it changes its colour. Indicators are of two types natural indicators (turmeric, china rose, litmus paper) and artificial indicators (phenolphthalein).

Natural indicators are those indicators which are extracted from natural. Some of the examples are turmeric, China rose, litmus paper.

TURMERIC: Turmeric is a well-known natural indicator. Let’s see a small activity to demonstrate the action of turmeric •	Take a small amount of detergent solution in a dish. Take a small piece of cotton dipped in turmeric. Dip the cotton piece into the solution. We see that the yellow colour changes to red. •	Take a small amount of vinegar solution in a dish. Take a small piece of cotton dipped in turmeric .Dip the cotton in the solution. We see that the colour remains the same.

It is known that detergent is basic and vinegar is acidic. Turmeric changes its yellow colour to red in base and the colour remains the same in acids.

China rose: China rose is another natural indicator. The solution of China rose can be made by the following procedure. •	Collect some China rose .Remove the petals. Take some amount of warm water in a beaker .Put the China rose petals into the beaker. Keep it for some time. The colour of the petals gets absorbed to the water and the colour changes to magenta. When China rose solution is added to acids the magenta colour changes to red and when it is added to baes the colour changes to green.

Litmus paper: Litmus is also called as a natural dye and it is one of the important, commonly used indicator. Litmus paper is extracted from the lichens. When lichens are dissolved in distilled water it will have a purple colour. The purple colour changes to red in acids and I n base it changes to blue. The solution is widely available. Lichens are commonly used as strips of paper and those strips of paper are called as litmus paper. Litmus papers are available in two colours red and blue.

Let’s see an activity to demonstrate the action of litmus paper. •	Prepare some amount of lemon juice in a dish. Take a blue litmus paper and put a small drop of the solution in it. We see that blue colour changes to red. Take a red litmus paper and do the same thing .We see that the colour does not change. •	 Take a small amount soap solution .Take a red litmus paper .Put a small drop of the solution in it. We see that the colour changes from red to  blue.

Red litmus paper turns to blue in acidic solution. Blue litmus paper turns to red in basic solution and the colour remains the same in neutral solution.