3b4 Titrations

The idea is to find out the concentration of one solution if we know the concentration of the other. We need to know the volume of each solution that just rreacts together exactly with none of either left over.

 You can do the calculation using moles (see next sheet).

If we know that the ratio of acid to alkali is 1:1 we can simply use:

Concentration of A x Volume of A = Concentration of B x Volume of B

One solution is measured out (with a pipette or a measuring cylinder) into a conical flask.
A few drops of a suitable indicator are added.
The other solution is added from a burette.
The titration is stopped when the indicator JUST changes colour.

Choosing an indicator is a little bit tricky.
For a strong acid: strong alkali titration, almost any indicator will do.
For a weak acid: strong alkali titration, use Methyl Orange.
For a strong acid: weak alkali titration, use Phenolphthalein.
Remember we are using strong and weak in their correct meanings (nothing to do with concentration)