What is the role of concentration in titrations?

The role of concentration in titrations is to determine the exact amount of a substance in a solution.

In a titration, the concentration of a solution is crucial as it allows us to calculate the exact amount of a substance present in that solution. This is done by adding a solution of known concentration (the titrant) to a solution of unknown concentration (the analyte) until the reaction between the two is complete. This point is known as the equivalence point.

The concentration of the titrant is known, and the volume of titrant needed to reach the equivalence point is measured. Using these two pieces of information, along with the balanced chemical equation for the reaction, the concentration of the analyte can be calculated. This is the fundamental principle of titration.

For example, if you were to titrate a hydrochloric acid solution of unknown concentration with a sodium hydroxide solution of known concentration, you would add the sodium hydroxide to the hydrochloric acid until all the acid has reacted. The point at which this happens is indicated by a colour change in an indicator, such as phenolphthalein, which is added to the acid solution at the start of the titration.

The volume of sodium hydroxide solution required to reach this point is then used, along with its known concentration, to calculate the concentration of the hydrochloric acid. This is done using the formula:

Concentration (mol/dm³) = Amount (mol) / Volume (dm³)

In this formula, the amount of sodium hydroxide is calculated from the balanced chemical equation for the reaction between sodium hydroxide and hydrochloric acid. The volume of sodium hydroxide is the volume measured during the titration.

Therefore, the concentration plays a vital role in titrations as it allows us to determine the exact amount of a substance in a solution.