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Acids and Alkalis

Using a Burette and a Pipette in a Titration.

What is a Burette?

A burette is a long glass tube with a tap at the bottom.
In a titration with an acid and an alkali the burette is filled with acid.
The tap can be turned open allowing the acid in the tube
to be added drop by drop into a conical flask.
The burette has graduation marks along it
which give the total volume of the acid at that point.
The marks may be 2cm³ apart with smaller marks within them
giving a reading of the volume which is accurate to 0·2cm³.

If the total volume of acid is 100cm³ to begin with
and 54·7cm³ after neutralisation, then the amount of acid used
is 100 - 54·7  = 45·3cm³

What is a Pipette?

A pipette is a long glass tube with a bulge in the middle.
The pipette has a filling line marked on it
which precisely gives the volume at that point.
A pipette is used to place an accurate amount of alkali
into the conical flask before the titration begins.

The alkali is sucked up into the pipette
until the liquid reaches the filling line.
You must never use your mouth to suck up alkali or any
other substance into the pipette.
You must always use a pipette filler.

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