A titre is the volume delivered from the burette. Subtract the initial reading from the final reading, even when the initial reading is greater than zero. The final reading tells you where the liquid level ended on the scale.
SEAB’s 2027 G3 Chemistry K324 syllabus says burette readings should normally be recorded to the nearest 0.05 cm³. It gives two titres within 0.20 cm³ as an example of sufficient agreement in an experiment with a good endpoint. Follow the instructions for the particular task.
- Record both readings for each trial.
- Subtract the initial reading from the final reading.
- Compare delivered volumes when deciding which trials agree.
- Check the instructions before calculating any mean.
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Read each trial as a pair
A trial can start at a non-zero reading. The initial and final readings belong to that same trial. If you copy one from the next column, the subtraction can give a believable number even though it describes no actual run.
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Worked example | Different starts, similar delivered volumes
In one practice trial the reading moves from 0.35 cm³ to 24.80 cm³, so the titre is 24.45 cm³. In another it moves from 1.10 cm³ to 25.65 cm³, so the titre is 24.55 cm³.
The final readings differ by 0.85 cm³. The titres differ by 0.10 cm³. Comparing the final readings alone would make the trials appear farther apart. If the task directs you to average these two titres, the mean is 24.50 cm³.
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Check the number before using it
Mark the titre row clearly. If a subsequent concentration calculation asks for volume in dm³, convert the delivered volume after identifying the titre required. For example, 24.50 cm³ equals 0.02450 dm³.
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Frequently asked questions
Does the burette have to start at zero?
Use the initial reading you actually recorded and follow the apparatus instructions for the task. The subtraction accounts for a non-zero start.