Question

How is a universal indicator obtained? How is the wide range of pH of solution tested by it?

Hint:

Universal indicator = Mixture of indicators. Colour change + pH chart → Determine pH (0–14).

Answer 1

Concept: A universal indicator is a mixture of several indicators that shows different colours at different pH values. It is used to determine the pH of a solution over a wide range. How Universal Indicator is Obtained:

• It is prepared by mixing a number of indicators such as methyl orange, phenolphthalein, bromothymol blue, etc.
• Each indicator works over a different pH range.
• The combined mixture gives a gradual colour change across the full pH scale.

Testing Wide Range of pH using Universal Indicator:

• A few drops of universal indicator are added to the solution.
• The solution shows a specific colour depending on its pH.
• The observed colour is compared with a standard pH colour chart.
• This helps determine whether the solution is acidic, neutral, or basic and gives an approximate pH value (0–14).

Conclusion: A universal indicator is made by mixing several indicators and is used to test a wide pH range by comparing the colour change with a standard pH chart.