Explain natural and synthetic indicators in detail.
Natural indicators are those indicators which are obtained from natural sources.Some of the examples of natural indicators are litmus,turmeric,red cabbage,beetroot juice.
1.Litmus- Litmus solution is a purple dye extracted from lichen, a plant belonging to the division thallophyte.It changes colour to red in acidic solution, blue in alkaline solution and purple in neutral solution.A blue litmus paper turn into red when it is dipped in acidic solution but will not change it's colour in basic solution. A red litmus changes into blue when dipped in basic solution but will not change colour in acidic solutions.
2.Turmeric- It remains yellow in acidic and neutral medium but in basic medium it's colour changes to deep red.
3.Red cabbage juice - In acidic medium it's colour changes to pink and in basic medium it's colour changes to bluish-green.
4.Beetroot juice- In acidic medium colour of beetroot juice does not change but in basic medium colour of beetroot juice changes to yellow
Synthetic indicators are acid- base indicators which are prepared from artificial/man-made substances and do not occur in nature.Some of the examples of synthetic indicators are phenolphthalein and methyl orange
1.Phenolphthalein - This indicator is colourless in acidic solution and gives pink colour in basic medium.Phenolphthalein indicator is widely used in titration process.
2.Methyl orange- In acidic solutions it's colour is red and in basic solution colour changes into yellow.