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IC6.5.4 Titrations
© Oxford University Press 2011
Titrations
IC6.5.4 Titrations
© Oxford University Press 2011
Titrations are used for chemical analysis:
• to find the purity of a solid chemical
• to find the concentration of a solution.
IC6.5.4 Titrations
© Oxford University Press 2011
A burette is filled with a solution.
This solution will react with the chemical being analysed.
The concentration of this solution is known.
IC6.5.4 Titrations
© Oxford University Press 2011
A sample of the chemical being analysed is placed in a conical flask.
If it is a solid, a balance is used to accurately measure its mass. It is then dissolved in pure water.
If the chemical being analysed is a solution, its volume is measured accurately.
IC6.5.4 Titrations
© Oxford University Press 2011
An indicator is added to the solution being analysed.
This will change colour when the reaction is complete.
IC6.5.4 Titrations
© Oxford University Press 2011
The solution in the burette is added to the contents of the flask, while the flask is swirled constantly.
Near the end point the solution is added drop by drop.
IC6.5.4 Titrations
© Oxford University Press 2011
At the end point the indicator changes colour.
The scale on the burette shows the volume of solution that has been added. This is the titre.
A calculation gives the purity or concentration of the sample being analysed.
IC6.5.4 Titrations
© Oxford University Press 2011
Titrations in industry are often carried out by robots. The robots transfer the solutions, measure volumes and detect the end point.