"In many fields of science and industry, it is essential to know the exact concentration of a substance in a solution. One effective method is conductometric titration. Unlike traditional titrations that rely on color changes, it measures the solution’s electrical conductivity to detect the equivalence point. This makes it especially useful for colored or opaque solutions, where indicators can’t be used."

What is conductivity in a solution?

Conductivity is the ability of a solution to conduct electricity. This depends on the presence of ions, which act as charge carriers. The more ions in the solution, the higher the conductivity. Hydrogen ions (H⁺) and hydroxide ions (OH⁻) are the most effective conductors due to their small size and high mobility.

• Brønsted-Lowry theory: Acids donate protons (H⁺), and bases accept protons.

Factors affecting conductivity

Two main factors influence the conductivity of an acid or base solution:

• Concentration: A more concentrated solution contains more ions, which increases conductivity.
• Strength: A strong acid or base fully ionises in water, producing a large number of ions and resulting in high conductivity. In contrast, weak acids and bases only partially ionise, producing fewer ions and lower conductivity.

Conductivity meter – device that measures a solution’s ability to conduct electricity

Electrodes – conductors that allow current to pass through the solution

Equivalence point – point in titration where reactants are in exact proportions

Turning point – change in the trend of conductivity during titration^

Factors Affecting Conductivity

• Concentration: More ions = higher conductivity
• Strength of the acid/base: Strong acids and bases ionise completely → more ions → higher conductivity
• Type of ions: Some ions (like H⁺ and OH⁻) are better conductors due to their small size and mobility

Principle of Conductometric Titration

• No need for a colour indicator
• Uses a conductivity meter with electrodes to measure conductivity
• Conductivity changes as titrant is added
• The equivalence point is found by observing a change in the trend (the “turning point”) on the graph

Graph Interpretation

• Y-axis: Conductivity
• X-axis: Volume of titrant added
• Graph shape depends on the acid/base pair:
• Strong acid + strong base → sharp V-shaped curve
• Weak acid + strong base → smoother, curved line before and after equivalence

Advantages of Conductometric Titration

• Works for coloured or opaque solutions
• No indicator needed