The pH scale is a numerical scale that measures how acidic or alkaline a solution is. The scale ranges from 0 (very acidic) to 14 (very alkaline).
If you add the right amount of an acid to an alkali, it will form a neutral solution. The same holds true in reverse, if you add the right amount of an alkali to an acid solution, it will form a neutral solution.
This means that if we had something from the left side of the pH scale (an acid) and added the right volume of something from the right side of the pH scale (an alkali), we would eventually form a substance in the middle. We would form a neutral solution that has a pH of 7.
An indicator is a substance that changes colour in response to changes in pH. The pH of a solution can be measured using an indicator or a pH meter.
A universal indicator is an acid-base indicator that can be used to determine the pH of a solution. When added to a solution, it produces a range of colours that can be compared to the pH indicator chart. This provides an accurate measurement of the solution’s pH.
When performing acid-base reactions, we can use universal indicators to determine when the reaction has reached a neutral state. If neutralisation has occurred, the solution should change to a green colour.
Litmus paper is paper that has been treated with a mixture of dyes. The two types of litmus paper are blue and red.
A pH meter is a more precise and accurate way to determine the acidity or basicity of a solution compared to using a universal indicator. When placed in a solution, it gives a numerical value representing the pH of the solution.
For example, if the reading is 2, the solution is acidic. The numerical data provided by the pH meter is more accurate than the colour-based method of using a universal indicator.