Chapter 22.2, Problem 8R

To determine

To Describe: Two techniques to measure the pH of a solution.

Explanation of Solution

Introduction:The pH of a solution determines how acidic or basic the solution is.

The pH of a solution is a measure of the concentration of ${\text{H}}^{+}$ ions in the solution.

If pH of a solution is less than 7, the solution is described as acidic, that is, concentration of ${\text{H}}^{+}$ ions is greater than concentration of ${\text{OH}}^{-}$ ions

If pH of a solution is equal to 7, the solution is neutral, that is, concentration of ${\text{H}}^{+}$ and ${\text{OH}}^{-}$ is same.

If pH is more than 7, the solution is basic, that is, concentration of ${\text{H}}^{+}$ ions is less than concentration of ${\text{OH}}^{-}$ ions.

The pH of a solution can be determined using universal indicator paper. A universal indicator is a mixture of organic dyes, which gives different colors with solutions of different with solutions of different pH values. The final color of the paper is matched with a chart to determine the pH.

The pH of a solution can also be determined using an instrument called the pH meter. The meter consists of two electrodes, a glass electrode and a reference electrode. The meter is operated by immersing the electrodes in the test solution and reading the voltage difference generated between the two electrodes.

A pH meter comes handy in testing the pH of soils and streams.

Conclusion:The pH of a solution can be measured using universal indicator paper or a pH meter.