Question

Smita took a spoon of turmeric powder and made a paste by adding little water to it. She cut thin strips of paper and applied this paste on them. After drying she put a few drops of given sample solution (i) – (iv) on these strips. What would be the changes in the color she observed?
(i) Amla juice
(ii) Lime water
(iii) Common salt solution
(iv) Baking soda solution

Answer 1

Hint: The turmeric solution or turmeric paste is a natural indicator it changes its color when acid applies on it as well as when a basic solution applies on it. There are many natural indicators from which turmeric paste is one of them. So, why turmeric acts as an indicator is due to the presence of curcumin which is yellow in acidic solution while reddish brown in basic solutions.

Complete step-by-step answer:
Among the list of substances given above we have to see which is acidic and which is basic. As we know that turmeric acts as a natural indicator thus it will show color changes when these solutions apply on it. Smita took turmeric on a paper strip now as she will apply the solutions on it. The turmeric paste either does not change the color which is an indication of acidic nature of the substance while if the color changes to red it will give indication of basic nature of solution.
First we have amla juice and we know that it is acidic in nature so when Smita apply it on turmeric no color change is seen it means color will remain yellow. Next for lime water it will change the color from yellow to red on the turmeric paper strip. For common salt, we know it is a neutral solution hence no color change is seen as a drop of solution is put on turmeric paper strip.
Lastly we have baking soda, we all use it while baking a cake. In this case as we know it is basic in nature hence the color observations changes from yellow to red.

Substance	Color Change
Amla Juice	Yellow
Lime water	Red
Common salt solution	Yellow
Baking soda solution	Red

Therefore, option A is correct.

Note: We can perform this experiment at home because all the substances are available at home we have many daily items like curd, washing soda etc. For estimating the results from a variety of daily products we can use turmeric as an indicator. We can find out the pH range of the solution for which we have to find out the nature of solution.