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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. ...read more.


In this case the concentration would be multiplied by two, because the ratio is 1:2. Ca(OH)2 + 2HCl � CaCl2 + 2H2O 0.0003375 x 2 = 0.000675 mol 1:2 0.0003375 So to find the volume that will need to be used in the experiment, the number of moles needs to be divided by the concentration. This will give the answer in dm3, so to get it into cm3 it needs to be multiplied by 1000. Ca(OH)2 + 2HCl � CaCl2 + 2H2O V = n c = 0.000675 0.2 = 0.0375 mol dm3 = 0.0375 x 1000 = 33.75 cm3 This shows approximately the amount of hydrochloric acid that will be needed to neutralise the calcium hydroxide in the experiment. Method 1. Firstly safety goggles must be worn at all times, along with any loose clothing or long hair tied back. If any of the solutions are spilt flood the area with water. ...read more.


Measure it all the way to the 50mls at the top making sure that the bottom of the meniscus is at the 50mls line. 8. Add five drops of the indicator into the calcium hydroxide, and lightly swirl to mix it. 9. Slowly run in the acid swirling. I chose to use 33.7 cm3 of hydrochloric acid that will only give one tiration out of a burette, rather than a smaller number that would give two or three tirations from the one burette because it works out as more accurate. For example if the actual volume needed in the titration was 13.7cm3 and the tiration came out with 13.5, there would be a difference of 0.02ml: %Diff = 0.2 x100 13.7 = 1.5% But if the volume in the titration came out as 33.5 when the actual volume was 33.7 and there was the same percentage difference of 0.2 then: % Diff = 0.2 x 100 33.7 = 0.6% This clearly shows that using 33.7 as the volume for hydrochloric acid is much more accurate. ...read more.

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