Chemistry – Acids, bases and salts - The characteristic properties of acids and bases | e-Consult

Universal indicator paper is a convenient method for determining pH because it provides a quick and easy visual indication of acidity, neutrality, or alkalinity. It eliminates the need for a pH meter or titration, making it readily accessible in a laboratory setting. The colour change is straightforward to interpret using a colour chart.

However, universal indicator paper is not perfectly accurate due to several limitations:

• Colour Variation: The exact colour observed can vary slightly depending on the concentration of the solution, the age of the indicator paper, and even the lighting conditions.
• Limited Precision: The colour changes are not finely graded. It's difficult to determine the pH with high precision using only the colour of the paper. You can only estimate the pH based on the colour range.
• Interference from Substances: Some substances in the solution might interfere with the indicator paper's colour change, leading to inaccurate results.
• Not suitable for coloured solutions: The colour of the solution itself can affect the reading.

Despite these limitations, universal indicator paper remains a valuable tool for quickly assessing the relative acidity or alkalinity of a solution, particularly in introductory chemistry experiments.