UNIT 4 BTEC Applied Science P1

P1


Sodium Carbonate Titration
Titration is a volumetric procedure, involving many diferent apparatuses to
make it work. The accuracy of the results depend on the concentration of the
regent used to do the titration.

Apparatus

 Goggles
 100cm3 Beaker
 250cm3 conical fask
 25cm3 Pipettes
 25cm3 Burette
 Clamp stand and holder
 Plastic flter funnel
 Phenolphthalein indicator solution
 Standard sodium carbonate solution
 1 M hydrochloric acid
 Pipette fller

Method

1. Transfer a 25cm3 aliquot (portion) of your sodium carbonate solution to a
250cm3 capacity conical fask..

2. A pipette is used to measure accurately a volume of this solution - for
example, 10cm3. A safety pipette fller is used to draw solution into the
pipette. This is emptied into a conical fask. A few drops of Phenolphthalein
indicator solution may be added to the conical fask. This will show a
change of colour when the titration is complete.

3. A second chemical is placed in a burette. This other solution is of a
chemical that will react with the synthesised chemical sample in the
conical fask. Often the solution in the burette is an acid or alkali, and it
must be of a precise, known concentration.

4. The solution from the burette is run into the conical fask. The solution is
added one drop at a time, with swirling to mix the solutions as the end-
point is approached. Eventually, a colour change shows that the correct
amount has been added to react completely with the synthesised
chemical in the sample.

5. The end-point of the titration is when the solution just changes from pink
to colourless. Repeat 1-4 thrice to get three separate results. The results
need to reliable which is the reason the test is repeated

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BTEC LEVEL 3 APPLIED SCIENCE EXTENDED DIPLOMA
Unit 4: Scientifc Practical Techniques