A LEVEL CHEMISTRY - PRACTICALS - TITRATION

Burette can be started from any point. The first titre must be from about 2­6 cm³ because we don’t know how much

volume will be needed. but rest of them can be started from any value which allows you to measure the volume. Let’s say that rough titre was 23 cm³ you can start the next titration from 15 cm³ because you know 15+23=38 which is inside the 50 cm³ range of burette. But if the rough titre is 38 cm³ and you start from 15 cm³ then you will be in trouble.

The two best titre must be consecutive as well as within 0.1 cm³. If first titre was 23.40, second was 23.10 and third was 23.50 then first and second can not be best titres. the reason is obvious. the second titre was more accurate than first and third.

If first two titres are within 0.1 cm³ then there is no need for third titration. If you think that any reading is not correct because it is out of pattern or too far away from line of graph circle that point on graph, again take that reading on the same table but on new row, and then plot new point.

All readings on table must be consistent. All your burette readings must be given to the nearest 0.05 cm³. For example if your volume comes out to be 24.1 cm³, then don’t write it as 24.1 cm³ rather write it as 24.10 cm³.

Always beware of endpoints. Whenever you know the end point is near, add the solution in burette drop by drop and close tap when the end point is reached without overly-titrating. 

All readings should be in a single organized table. 1 MARK would be deducted otherwise. An example of a good table for recording readings while performing titrations is given below (you may memorize this table!) :

	1	2
Initial Burette Reading / cm3
Final Burette Reading / cm3
Titre / cm3
Best Results (✓)

In the table, the headings and their units have separate marks. Write Temperature/C or temperature (C) but T/C or temperature C are not allowed. Full name of quantity must be used. Writing V for volume might be acceptable but ‘T’ is not acceptable as it may have been used for temperature or for time.