Performing a titration

A bluffers guide!

Preparing a standard solution

Accurately weigh a weighing bottle, recording the mass

Add approximately x g of your substance to the bottle.

Re-weigh and record the mass Tip the substance into a 100cm3 beaker

Rinse out the weighing bottle with distilled water a couple of times. Add the washings to the beaker. (It is important all the solid goes into the beaker)

Pour about 25cm3 of distilled water into the beaker (but do not exceed half-full)

Stir with a glass rod until all the solid has dissolved

Transfer the contents of the beaker into a 250cm3 volumetric flask, carefully, using a funnel.

Rinse the beaker and glass rod a couple of times, adding the washings to the flask, then wash the funnel twice as well.– This technique ensures all the solid is

transferred.

Add distilled water to the flask to about 1cm below the graduation mark

Using a clean pipette add distilled water until the bottom of the meniscus is just touching the graduation mark. – DO NOT EXCEED THIS MARK ON PAIN

OF DEATH!!

Stopper the flask, with the correct sized stopper, (Hint: Check this point before starting!!) and invert several times

You have now made a standard solution, the molarity of which you know exactly.

Having done all this correctly: stop and look very smug!!

The titration itself

Use a pipette and pipette filler to withdraw 25.0cm3 of standard solution from the volumetric flask and transfer it to a conical flask

Use a clean beaker to fill a burette with the solution that you are titrating with.

Good practice includes

Not looking up at the beaker (This can be dangerous). You should be filling it from above, ie looking down on it!!

Ensure the tap is closed (Please!!)Use an appropriate clamp!!Use a funnel to perform this procedureRun a little solution into the beaker to remove

any air bubbles

More ways to get an A*

Take the funnel out before recording the starting volume

It does not have to go to 0.0cm3

Make sure you are aware you can record these volumes to 2dp, so therefore ensure you do record all volumes to 2dps!!!

Be consistent, always record to the bottom of the meniscus

Couple more things

Use a white tile when doing the titrationAdd the solution from the burette in small

amounts, swirling all the while

Finally

The end point will be an obvious sudden colour change.

Record the volume used and work out the volume used. This is your rough titration.

Do several more titrations until you achieve concordance (two readings within 0.1cm3).

Add the solution dropwise as the end point approaches, swirling at the same time.

Indicators!!