Performing the Titration Flashcards
he key piece of equipment used in the titration is the burette
Burettes are usually marked to a precision of 0.10 cm3
Since they are analogue instruments, the uncertainty is recorded
to half the smallest marking, in other words to ±0.05 cm3
The end point or equivalence point occurs when the two solutions have reacted
completely and is shown with the use of an indicator
A white tile is placed under the conical flask while the titration is performed,
to make it easier to see the colour change
Measuring a known volume (usually 20 or 25 cm3) of one of the solutions with a ……… and placing into
a volumetric pipette and placing it into a conical flask
The other solution is placed in the burette
To start with, the burette will usually be filled to
0.00cm cubed
A few drops of the………………. are added to the solution in the …………..
indicator
conical flask
The tap on the burette is carefully opened and the solution added, portion by portion, to the conical flask until the indicator
starts to change colour
As you start getting near to the end point, the flow of the burette should be
slowed right down so that the solution is added dropwise
You should be able to close the tap on the burette after one drop has caused the colour change
Multiple runs are carried out until concordant results are obtained
Concordant results are within 0.1 cm3 of each other
percentage uncertainty equation
percentage uncertainty = uncertainty / measured value x 100
Using a burette to find the initial reading and final reading
In all these example you have to read the instrument twice to obtain the quantity
If each you time you read the instrument the measurement is ‘out’ by the stated uncertainty, then your final quantity is potentially ‘out’ by twice the uncertainty