Question

Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.

Answer 1

Turmeric Indicator :

• It is an acid-base indicator.
• It is yellow in color.
• It turns to deep red color when it interacts with bases.
• When acids are introduced, the indicator's red form can turn back into yellow.

Properties of Liquids available :

• Hydrochloric Acid $\left(\mathrm{HCl}\right)$ is acidic in nature with a pH of about $3$.
• Sodium Hydroxide $\left(\mathrm{NaOH}\right)$ is basic in nature with a pH of $13$.
• Sugar solution $\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$ is neutral as it is neither acidic nor basic and has a pH of $7$.

Determination of Liquids :

• Over these three liquids, i.e. Hydrochloric Acid $\left(\mathrm{HCl}\right)$, Sodium Hydroxide $\left(\mathrm{NaOH}\right)$ and Sugar $\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$, add the turmeric indicator.
• If the color of the indicator changes to deep red or crimson red then that liquid is Sodium Hydroxide $\left(\mathrm{NaOH}\right)$ as the turmeric indicator changes its color to red when it interacts with a base and $\left(\mathrm{NaOH}\right)$ is a base.
• Now add $\left(\mathrm{NaOH}\right)$ in two test tubes and put a drop of $\left(\mathrm{HCl}\right)$ and $\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$ respectively in each one of the tubes and then add turmeric indicator in both of them.
• Observe the increase in temperature in one of the test tubes. This increment is due to the neutralization reaction occurring due to the presence of $\left(\mathrm{HCl}\right)$ i.e. acid in the tube with no change in the color of the indicator.
• The tube whose color changes to red indicates the presence of $\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$ i.e. sugar with no change in temperature.