Question 1 What is an indicator?
Question 2 Name the common indicators used to test acid,bases and salts?
Question 3 What are olfactory indicators.Give examples?
Question 4 What is the colour of Phenolphthalein in acidic and basic medium?
Question 5 What is the colour of methyl orange in acidic and basic medium?
Acid,Bases and Salts
On the basis of chemical properties,all the compounds can be classified into three groups:
1)Acids
2)Bases
3)Salts
Indicator
An indicator is a dye that changes colour when it is put into an acid or a base.
An indicator tells us whether a given substance is an acid or a base by change in its colour.
The three common indicators to test for acids and bases are
1)Litmus
2)Methyl Orange
3)Phenolphthalein
Indicator | Acid | Neutral | Basic |
Red Litmus | Red | Red | Blue |
Blue Litmus | Red | Blue | Blue |
Phenolphthalein | Colourless | Colourless | Pink |
Methyl Orange | Red | Orange | Yellow |
1)Orange juice turns blue litmus to red,so orange juice is acidic in nature.
2)Sodium Hydroxide turns red litmus to blue,so it is basic in nature.
Litmus is a natural indicator whereas Methyl orange and phenolphthalein are synthetic indicators.
Olfactory Indicators
Those substances whose smell or odour changes in acidic or basic solution are called olfactory indicators.
For Ex:Onion and Vanilla extract
That’s good
very good website. nice explanation and easy to grasp!
well done team 🙂