Question

You are provided with three test tubes containing sugar solution, baking soda solution and tamarind solution. Explain how can you identify the nature of each of these solutions using litmus paper.

Answer 1

Litmus paper is used to identify the nature of a solution as acidic, basic or neutral. It is available as red and blue paper strips.
The following table shows the colour of litmus in different medium:
$\begin{array}{cccc}& \text{Acidic}& \text{Neutral}& \text{Basic}\\ \text{Red Litmus}& \text{Red}& \text{Red}& \text{Blue}\\ \text{Blue Litmus}& \text{Red}& \text{Blue}& \text{Red}\end{array}$

The observations after dipping red and blue litmus papers in the solutions are as follows:
$\bullet$ Sugar solution - Colour of both the litmus remains unchanged. Therefore it is neutral in nature.
$\bullet$ Baking soda solution - Red litmus turns blue and blue litmus remains unchanged. Therefore, it is basic in nature.
$\bullet$ Tamarind solution - Blue litmus turns red and red litmus remains unchanged. Therefore, it is acidic in nature.