The aim of this experiment is to determine the concentration of a limewater solution by method of titration.

The volume of HCl is too small to titrate and therefore I will multiply the volume by x100.  To do this I need to divide the concentration of the acid by 100.  (2moldm-3 will be 0.02moldm-3)

Method of dilution:

Apparatus:

• 5cm3 graduated pipette
• 50cm³ burette
• 250cm³ volumetric flask
• funnel
• burette stand
• 250cm³ of limewater
• Hydrochloric acid and concentration 2mol dm-3
• 1g dm-3 of Calcium hydroxide (present in limewater)
• 250cm3 conical flask
• distilled water
• 25cm3 pipette

To dilute the Hydrochloric acid-

1. Pour 2.5cm3 of HCl into a volumetric flask using a 5cm3 graduated pipette.
2. .Fill up to the marked like on the 250cm3 volumetric flask with distilled water.
3. This has diluted the 2mol dm -3 HCl to 0.02mol dm -3 .

Titration:

1. Firstly the burette should be placed securely in the stand, 10 cm above the surface of the table.
2. Fill the burette with 50cm³ of HCl, using a funnel to prevent spillage of the acid.  Record the initial volume in a results table.
3. Pipette 25cm³ of limewater into a 250cm³ conical flask.  
4. Five drops of methyl orange indicator should be added to the conical flask.  The limewater should turn yellow.  Place the conical flask directly underneath the burette.
5. Carefully allow the diluted HCl dispense into the conical flask, placing your left hand around the neck of the burette controlling the flow of the HCl and continuously swirling the conical flask with the right hand.
6. When the solution in the conical flask changes colour, (the solution should change from yellow to red), close the tap on the burette preventing anymore diluted HCl from dispensing into the conical flask.  Record the final volume of HCl in the results table.  Then calculate the titres by minusing the final volume from the initial volume.
7. Dispose of the contents in the conical flask; rinse the conical flask with distilled water.  Add 25cm³ of limewater and five drops of methyl orange.  Place the conical flask underneath the burette.
8. Repeat steps 5, 6 and 7 until you have three titres that are all within 0.1cm³ of each other.  This means that the results obtained are concordant to each other.

Safety, Hazards and Preventions:

Bibliography:

1. I found out what indicator would be suitable to use for this experiment from the following website, I also found out what colour the CaCl2   solution should turn once enough HCl has been added:

2. The following website gave me a clearer understanding on how indicators work and what colour HCl (a strong acid) and Ca(OH)2 should turn when methyl orange is present in the solution:

3. The website address below explained Hazards and preventions of the following chemicals HCl and the indicator methyl orange:

4. The book named below, gave me a good definition of a titration and gave a clear simple explanation on why titrations are carried out and how to carry out a titration.

‘The complete A-Z chemisty handbook second edition’ Page 355, By Andrew Hunt.