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Synthetic indicators are indicators that are made from artificial substances. Synthetic indicators include phenolphthalein and methyl orange.
When litmus papers are used to test a neutral solution, the same result (the below pictures) occurs.
Litmus papers in neutral solutions
Neutral solutions are those in which the concentrations of hydrogen and hydroxide ions are the same. Examples, sodium chloride solution, sugar solutions and water.
Phenolphthalein indicator:
Phenolphthalein is colourless in an acid medium. The colour of phenolphthalein in a basic medium is pink.
Methyl orange indicator:
Methyl orange is pink in an acid medium. Methyl orange appears yellow in a basic medium.
Test for acid and base using methyl orange indicator
Acid-base indicators:
Indicators | Colour in acid | Colour in base |
Litmus paper | Blue → Red | Red → Blue |
| Phenolphthalein | Colourless | Pink |
Methyl orange | Pink | Yellow |
Reference:
https://media.sciencephoto.com/image/c0391218/800wm/C0391218-Phenolphthalein_Indicator.jpg
Reference:
https://slideplayer.com/slide/4356752/14/images/27/Acid+%E2%80%93+Base+Indicators+Methyl+Orange+Indicator..jpg
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