[Chemistry Form 4] Acid Meets Base

One easy way to distinguish acid and base from one another is through indicators. An example is the litmus indicator.

Also, many natural dyes found in fruits vegetables, and flowers can act as indicators. For example, red cabbage extract is red in an acidic solution and blue in a base solution.

When an acid reacts with a base, the reaction yields water and an ionic compound known as salt. This acid-base reaction is called a neutralisation reaction.

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Indicator: Litmus
Acid solution: RED
Neutral solution: PURPLE
Alkali solution: BLUE

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Indicator: Phenolphthalein
Acid solution: Colourless
Neutral solution: Colourless
Alkali solution: PINK

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Indicator: Methyl Orange
Acid solution: PINK
Neutral solution: ORANGE
Alkali solution: YELLOW

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Indicator: Bromothymol Blue
Acid solution: YELLOW
Neutral solution: GREEN
Alkali solution: BLUE

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Indicator: Cresol Puple
Acid solution: YELLOW
Neutral solution: GREEN
Alkali solution: PURPLE

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