Question

Is the distilled water acidic/basic/neutral? How would you verify it?

Answer 1

Hint - To solve this problem, firstly we have to understand the chemical properties that a substance should have, to be categorized as acidic, basic or neutral. Then with the further steps using a specific indicator (litmus paper), we will be finding the category of the distilled water and hence approaching our answer.

Complete step by step solution:
> Acid: The most common characteristic is their sour taste. An acid is a substance that releases hydrogen ion $\left( {{H^ + }} \right)$ in its aqueous solution. It turns blue litmus paper red.
$HCl\left( {aq} \right) \leftrightarrow {H^ + } + C{l^ - }$
> Base: The most common characteristic of bases is their bitter taste and soapy feel. A base is a substance that releases hydroxyl ion$\left( {O{H^ - }} \right)$ in their aqueous solution. Color of red litmus paper turns to blue.
$NaOH\left( {aq} \right) \leftrightarrow N{a^ + } + O{H^ - }$
Salts: It is formed by the neutralization reaction of acids and bases.
$HCl + NaOH \leftrightarrow NaCl + {H_2}O$
> A neutral substance is the one which shows no properties of acid or a base. It has an equal number of Hydrogen $\left( {{H^ + }} \right)$ and Hydroxyl $\left( {O{H^ - }} \right)$ ions. And when reacted with Litmus paper, it shows no change.
Now we will find whether distilled water is acidic/basic/neutral.

Let’s carry out the test for distilled water. We can verify it, by taking a small amount of distilled water into two test tubes. Add blue litmus paper to one test tube and red litmus paper to another test tube. We will observe that there is no change in the color of either blue or red litmus paper which shows distilled water is neither acidic nor basic, hence neutral.

NOTE – Litmus paper (used to test the pH of liquids) is made by treating the paper with natural dyes. Red litmus turns blue which indicates a basic pH whereas blue turns red for the acidic pH. It can be reused. For example, litmus that has changed from blue to red can be used as the red litmus and vice versa.