P3 - Estimate the puritta of samples usitng scitentiifc technitques.
D2 - Evaluate the accuraca of the methods used to estimate the puritta of the
samples.
Tittrations for Soditum Hadroiitde
In this experiment I have investiated how much Hydrochloric acid would take in
order to neutralise 25ml of the Sodium Hydroxide and 20ml of the Sodium Hydroien
Carbonate. This was done throuih the investiaton usini the phenolphthalein
indicator which went from pink to colourless when an end point was reached.
Equipment required for the ttrrtonon
1. Burette
2. Conical flask
3. 1 molar HCl
4. 1 molar Sodium Hydroxide
5. 250 ml beakers
6. Phenolphthalein indicator
7. Clamp stand
8. Burette plastic holder
Method for the Titrrton of NrOHn
1. Firstly, you set up the required apparatus for the titration.
2. You then use a measuring cylinder to transfer 25ml of liquid sodium
hydroxide into a conical flask.
3. Secondly, you use 1 Molar HCl to fill up the burette up to the mark of
zero at the top of the burette. Make sure that you place the burette
below the level of your face to avoid spillages on your skin. Also,
when filling up the burette make sure to look out for the meniscus
which should just be above the 0 line.
4. Afterwards, you add one to two drops of the Phenolphthalein indicator
which should produce a tint of pink/magenta colour to the sodium
hydroxide.
5. Thirdly, you have to place the conical flask below the tip of the burette
and twist the switch in order to release the flow of the HCl into the
Sodium Hydroxide.
6. You have to gently shake the flask in gentle circular motions (avoid
spillages) in order for the two chemicals to mix together, at first drain a
lot of the Hydrochloric acid then every now and so constrict the tap
allowing only a few drops at a time.
7. Depending on the accuracy of your measurements you should get a
titre which is the reading you take from the burette when the Sodium
Hydroxide goes from pink to colourless.
8. Before carrying any of the titrations make sure that the HCl is filled up
to the mark of zero, you would have to fill up the burette after every
reading completed.
9. Record the results on suitable table.