Question

The given solution changes the colour of turmeric from yellow to red the solution is:
A. acidic in nature
B. basic in nature
C. neutral in nature
D. turmeric is not an indicator for acid or base

Answer 1

Hint: Turmeric is in yellowish colour; its yellow colour is due to the presence of the natural pigment called curcumin. Turmeric is a perfect example of a natural pH indicator. It is found that turmeric changes their colour when the pH changes.

Step by step solution:
- PH of a substance is the measure of its acidic or alkaline medium, that has the range from 1-14 pH.
- Acidic medium have a range of pH about less than 7, and basic medium is found to have pH range higher than 7.
- When turmeric paper is dipped in acidic solution like vinegar or lemon juice then it doesn’t change its colour and remains yellow in colour.
- When turmeric is found to be soluble in basic solution, for example if it is dipped in basic solution like sodium hydroxide, then the turmeric turns red, this change in colour is due to the changes in pH .
- Hence, we can conclude that option (B) is correct, that is the solution is basic in nature which changes the colour of turmeric from yellow to red .

Additional information:
- We have seen that turmeric can detect the acidic or basic nature of the other substances by change in its colour. Hence, we can call it an acid-base indicator.
- We should not taste any substance in the laboratory soluble because it can be harmful. Hence, we can say that these are economically very much important to check whether a given substance is acid or a base.

Note:
- Turmeric is yellow for acidic or neutral solutions and brown to reddish for alkaline solutions, with the transition between pH of 7.4 and 9.2.
- We must always remember that pH of 7 is neutral, a pH greater than 7 is basic and less than 7 is acidic.