Question

Why should distilled water be used when conducting chemical tests?

Answer 1

Explanation:

Water is used in many tests as solvent for dissolving solutes.

No ions, compounds or salts are present in distilled water. Therefore, test result will not be affected by distilled water.

If plain water is used instead of distilled water, the ions or other salts present in plain water, may undergo chemical reaction with the reagent and may affect the test result.

Consider an example,

Concentration of $Fe^{2+}$ is determined by potassium permanganate using titration method

solution of both $Fe^{2+}$ and potassium permanganate are made in water.

Potassium permanganate is titrant and $Fe^{2+}$ is used as titrand.

Concentration of $Fe^{2+}$ is determined by end point. if the water used for making solution is not distilled, it may affect end point, which results in incorrect determination of concentration of $Fe^{2+}$.

Therefore, distilled should be used for chemical tests.