Apparatus
The apparatus that I would be using for this experiment include:
25cm3 pipette,
1000cm3 volumetric flask
A 250cm3 conical flash,
A 20cm3 burette,
A tile, clamp and stand,
A suitable indicator, (my first intension was to use phenolphthalein, but after some research it is better to use Methy Orange)
Limewater (250cm3 with 1g dm3 of calcium hydroxide)
HCl (concentration of 2.00 mol dm3) and Distilled water- the HCl is main variation in the experiment.
PLANNING
Before doing any experiments you must make sure that the procedure you are using is safe and make sure you must take safety precaution in the course of the experiment, this is for the simple reason to protect yourself and those around you from any harmful chemicals. Some of these procedures include
- Wearing glasses and gloves to prevent your eyes and hands getting in contact with any dangerous chemicals.
- It would be best to tie your hair in order to prevent any chemicals getting in contact with them as they can be corrosive. Therefore it is advisable to be aware when you are working with any chemicals.
When slaked lime is dissolved in water it forms limewater, and when calcium oxide is mixed with water it is violent and this produces calcium Hydroxide which is slaked lime and if you more and more water the calcium hydroxide would produce the Limewater in an aqueous solution, and it is this limewater that I am going to use for this experiment. So the whole point of the experiment is to find out the concentration of limewater and this can be done by reacting the Hydrochloric acid with the Limewater and the equation for this is
When it comes to deciding which indicator is best suited for the reason you take in to account that some measurements will be determined by colour and the one indicator that come to mind is phenolphthalein because it is mainly used for colour indication. However from my research I found that there another chemical that could also be used for the experiment is ‘methyl orange’ because this indicator has a relative pH scale which is around 4-7 keeping in mind that the limewater is also a weak acid base so this more suitable compared to the phenolphthalein as it has a higher pH scale compared with the limewater.
It is also advisable that the hydrochloric acid to be diluted in order to prevent the reaction from happening too fast.
In order to start the experiment it is important that my 2.00mol dm3 hydrochloric acid is diluted because it is too concentrated and the limewater requires a weaker base and doing this is more likely to give a more reliable and accurate results. I therefore think it would be best if I used a 0.1-0.5mol dm3 of the Hydrochloric acid. It is important that the amount of the chemicals used and the amount of limewater stay in range that is best to keep the experiment and its results constant, and that’s why I think it would best to use 50 dilutions meaning that I will be using 20cm3 of HCl with 980cm3 of distilled water or 50cm3 of HCl with 950cm3 distilled water. Doing this would mean that you will are making a 1000cm3 of diluted HCl acid and would be able to used a 25cm3 when it comes to the titration of the limewater.
Diluting the 2.00mol dm3 Hydrochloric acid
Diluting the Hydrochloric acid can be achieved by placing a 20cm3 of HCl measurement I have chosen to use in the flask using the pipette to make very accurate measurement.
PROCEDURE FOR THE DILUTING
1. Firstly you pour the 20cm3 of the 2.00mol dm3 of the Hydrochloric acid in to the 1000cm3 volumetric
flask.
2. After that you should add the distilled water to the 200cm3 HCl in the volumetric flask, and this should
be done until the solution reaches at least a mark of 1000cm3 on the volumetric flask. And this would
mean adding the 980cm3 of distilled water. The concentration that I am making is 1000cm3 which I
will achieve by adding a 980cm3 of distilled water with 20cm3 of the 2.00mol dm3 of the hydrochloric
acid.
THE METHOD FOR THE EXPERIMENT
- Firstly set up the apparatus by attaching the clamp and stand supporting the pipette over the volumetric flask, make sure that you wear a protective glove and goggles when dealing with the chemicals.
-
Use the 25cm3 of the aqueous limewater into a 250cm3 conical flask.
- Use a minimum of 3 drops to a maximum drops of the methy Orange or the phenolphthalein
indicators to the limewater.
-
Then titrate with respect to the 0.1mol dm3 of the HCl I have chosen to use.
- Then make sure you write down how much of the HCl acid used and write down your result as soon the solution becomes colourless
- Record your results in a table
-
Repeat the titration for at least three times making sue that you use 0.1cm3 to keep the results constant.
- Then you can workout the average for the titration.
