rate if useful!!!!!!!!!!!!!!!!!

Measurement

pH can be measured:

 

• by addition of a pH indicator into the solution under study. The indicator color varies depending on the pH of the solution. Using indicators, qualitative determinations can be made with universal indicators that have broad color variability over a wide pH range and quantitative determinations can be made using indicators that have strong color variability over a small pH range. Precise measurements can be made over a wide pH range using indicators that have multiple equilibriums in conjunction with spectrophotometric methods to determine the relative abundance of each pH-dependent component that make up the color of solution ,^{[citation needed]} or


• by using a pH meter together with pH-selective electrodes (pH glass electrode, hydrogen electrode, quinhydrone electrode, ion sensitive field effect transistor and others).


• by using pH paper, indicator paper that turns color corresponding to a pH on a color key. pH paper is usually strips of paper that has been soaked in an indicator solution, and is used for approximations.

As the pH scale is logarithmic, it does not start at zero. Thus the most acidic of liquids encountered can have a pH as low as −5.^{[citation needed]} The most alkaline typically has pH of 14. Measurement of extremely low pH values has various complications. Calibration of the electrode in such cases can be done with standard solutions of concentrated sulfuric acid whose pH values can be calculated with the Pitzer model.^[8]

As an example of home application, the measurement of pH value can be used to quantify the amount of acid in a swimming pool.