What is universal indicators . What is the colours for strong acid , Strong base and neutral salt
Answers
Answer:
A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. Although there are several commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1933.[1] Details of this patent can be found in Chemical Abstracts.[2] Experiments with Yamada's universal indicator are also described in the Journal of Chemical Education.[3]
A universal indicator is typically composed of water, propan-1-ol, phenolphthalein sodium salt, sodium hydroxide, methyl red, bromothymol blue monosodium salt, and thymol blue monosodium salt.[4] The colours that indicate the pH of a solution, after adding a universal indicator, are
pH range Description Colour
< 3 Strong acid Red
3–6 Weak acid Orange or yellow
7 Neutral Green
8–11 Weak alkali Blue
> 11 Strong alkali Violet or Indigo
The colours from yellow to red indicate an acidic solution, colours blue to violet indicate alkali and green colour indicates that a solution is neutral.
Universal indicator components
Indicator Low pH colour Transition pH range High pH colour
Thymol blue (first transition) Red 1.2 – 2.8 Yellow
Methyl orange Red 3.2 – 4.4 Yellow
Methyl red Red 4.8 – 6.0 Yellow
Bromothymol blue Yellow 6.0 – 7.6 Blue
Thymol blue (second transition) Yellow 8.0 – 9.6 Blue
Phenolphthalein Colourless 8.3 – 10.0 Fuchsia
Wide-range pH test papers with distinct colours for each pH from 1 to 14 are also available. Colour matching charts are supplied with the specific test strips purchased.
Explanation:
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A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. Although there are several commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1933. Details of this patent can be found in Chemical Abstracts.Experiments with Yamada's universal indicator are also described in the Journal of Chemical Education.
A universal indicator is usually composed of water, 1-Propanol, phenolphthalein, sodium hydroxide, methyl red, bromothymol blue, Sodium bisulfite, and thymol blue .
The colours from yellow to red indicate an acidic solution, colours blue to violet indicate alkali and green colour indicates that a solution is neutral.