Determine the concentration of a limewater solution.

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CHEMESTRY COURSEWORK

Determine the concentration of a limewater solution.

Equation  

Ca(OH)2 + 2HCl → CaCl2 + 2H2O

calcium hydroxide + hydrochloric acid → calcium chloride + water

Apparatus

Burette 50cm3

Pipette 20mls/25mls

Volumetric Flask 2000cm3

Conical Flask

Boss and Clamp

Funnel

White tile

Indicator

2000cm3 0.02 mol Hydrochloric acid

250 cm3 Limewater

Firstly, the acid that I was given is too strong for the reaction to be reliable, which means that it has to be diluted.  To get a suitable concentration of the acid which will titrate into the base:

                    2.00  = 0.02 mol

100

20:2000

=1:100

So to make 0.02mol of hydrochloric acid; measure 20cm3 of 2mol dm3 accurately into a pipette. Making sure the bottom of the meniscus is in line with the 20cm3 line.

Put this into a 2000cm3 volumetric flask and fill it up to the 2000cm3 line with water. This then needs to be mixed thoroughly by turning it upside down 100 times.

In order to decide on the volume of hydrochloric acid to use, firstly the concentration of the calcium chloride needs to be found: I was provided with 250cm3 of calcium chloride so I decided to use 25cm3, this will give up to 10 titrations. However although doing the titration this many times would make the results very accurate, it would take up a lot of time. So to do the experiment 4 times would give an accurate enough result, if the first test was done as a practice.  Here I have found the number of moles in 25cm3 of calcium hydroxide.

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                                         Ca(OH)2 + 2HCl → CaCl2 + 2H2O

                         n = M

                               m

                         n =   1

      ...

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