Answer:
Phenol red /
Thymol blue
Explanation:
pH indicator referred to halochromic chemical compound which is added in small amounts to a solution for the determination of pH visually.
An indicator can be described as a chemical detector for both hydronium and hydrogen ions as far as Arrhenius model is concerned, an indicator are usually weak acids or bases, and when they are which dissolved in water , there would be a dissociation process and ions is formed.
There are different types of indicator used in the laboratory depending on the pH values of the solution examples are thymol blue, bromothymol blue, thymol blue, phenolphthalein and methyl red
Thymol blue is an indicator that transit between red to yellow when the pH is between the range of 1.2–2.8 and also transit from from yellow to blue when the pH 8.0–9.6. It an indicator that usually have brownish-green or reddish-brown crystalline powder
Phenol red is pH indicator which is yellow in colour when it is below 6.8 pH and has a very bright pink colour when used with pH above 8.2
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