Discuss the limitations of acid-base indicators... - SS2 Chemistry Acids, Bases, and pH Question

While acid-base indicators are useful tools for approximating the pH of a solution, they have certain limitations that should be considered:

1.    Limited pH Range: Each indicator has a specific pH range over which it changes colour. Outside this range, the indicator may not provide accurate results. Using an indicator that is not suitable for the pH range being tested can lead to incorrect pH readings.

2.    Subjectivity of Colour Perception: Colour changes in indicators are often subtle and subject to individual interpretation. Different observers may perceive colour changes differently, leading to variations in recorded pH values.

3.    Interference from Other Substances: Some substances present in the solution can interfere with the colour change of the indicator, resulting in inaccurate readings. Substances that absorb light in the same wavelength range as the indicator can affect the observed colour.

In situations where higher accuracy is required, pH metres or universal indicators may be preferred over specific acid-base indicators:

●     pH Metres: pH metres offer precise and quantitative measurements of pH by measuring the electrical potential difference between electrodes immersed in the solution. They provide real-time and digital pH values, eliminating subjective interpretation and offering a wider pH range for accurate readings.

●     Universal Indicators: Universal indicators are mixtures of several acid-base indicators that provide a colour spectrum over a wide pH range. They offer a rough estimation of pH across a broader range of acidity or basicity, making them suitable for quick assessments without the need for precise measurements.