In the gravimetric method, why is the reaction solution tested with litmus paper?

The gravimetric method is a set of method in analytical chemistry for the quantitative determination of analytes. There are four fundamental types of gramvimetric method, these are: physical gravimetry, thermogravimetry, precipitative gravimetry analysis and electrodeposition.

In gravimetric method, the reaction solution is tested with litmus paper in order to determine the pH of the solution.