Performing Titrations

What do titrations allow you to find out?

Exactly how much acid is needed to neutralise a quantity of alkali.

What do you put in the flask?

The alkali, using a pipette, and an indicator

What should you do first?

A rough titration to get an idea where the end point is

Where is the end point?

The point where the alkali is exactly neutralised and the indicator changes colour.

How would you do a rough titration? (1)

Take an initial reading to see how much acid is in the burette to start off with.

How would you do a rough titration? (2)

Add the acid to the alkali, giving the flask a regular swirl.

How would you do a rough titration? (3)

Stop when your indicator shows a permanent change, the end point.

How would you do a rough titration? (4)

Record the final reading from the burette

What do you do after a rough titration?

An accurate titration

What do you do for an accurate titration?

Run the acid in to within 2cm3 of the end point, then add the acid dropwise.

What happens if you don't notice exactly when the solution changed colour?

You've overshot and your result won't be accurate.

What do you work out in an accurate titration?

The amount of acid used to neutralise the alkali.

How would you work out the amount of acid?

The final reading minus the initial reading

What's the volume known as?

The titre

What's best to do and what should your readings be?

It's best to repeat the titration a few times, making sure you get a similar answer each time and your readings should be within 0.1cm3 of each other.

What should you ignore, when calculating the mean?

Anomalous results