Find the concentration of a sample of limewater solution in g dm3.

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Plan
The aim of this experiment is to find the concentration of a sample of limewater solution in g dm3. I am required to design my own experiment and choose a range of appropriate equipment and apparatus. The indicator will be supplied to me. I am provided with 250 cm3 of limewater, which has been made such that it contains approximately 1g dm3 of calcium hydroxide. Also available is hydrochloric acid which has a concentration of 2.00 mol dm3, this concentration is too much though so it is necessary to dilute it.

Apparatus and chemicals-
Pipette 25cm3, Volumetric flask 500cm3, Conical flask 250cm3, Burette, White tile, Clamp and stand, Indicator (methyl orange), Limewater (250cm3 with 1g dm3 of calcium hydroxide), Hydrochloric acid- standard solution (conc. 2.00 mol dm3),Distilled water.

Acid + Metal Hydroxide => Salt + Water
Limewater + Hydrochloric acid => Calcium chloride + Water + Hydrogen
Ca(OH)2(aq) + 2HCl(aq) => CaCl2 + 2H2O(aq)

In order for the experiment to be accurate and reliable it will be necessary to dilute the Hydrochloric acid significantly. It is in my belief that a concentration of 0.1mol dm3 would enable me to achieve reliable results. This would require a dilution factor of twenty. I will be making 500 cm3 of dilute hydrochloric acid. I will also be using 25cm3 of Limewater.
In order to reduce errors it is necessary to choose accurate and reliable equipment. That is why I have chosen the pipette, volumetric flask and burette. All of these instruments have an accuracy of ±0.05cm3, which is suitable for my experiment and should produce accurate and reliable results. In making my choice of indicator I also had to be very careful. The Limewater used will be a relatively weak base so it will be appropriate to use methyl orange as it has an end point on the ph scale between 8-5. Whereas phenolphthalein indicator has an end point much higher up in the ph scale. So if I were to use the phenolphthalein indicator then the end point (colour change) would be reached before the equivalence point (when the chemicals, acid-base break up).

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Implementing- Safety is very important and it is necessary to follow safety procedures. It is important to wear eye protection when working with any acid. Also long hair should be tied back. Also as the chemicals used are corrosive it is important to take extra care while working around them.
In order to start with the experiment it is required of me to dilute the HCl. An accurate way of doing this is to use a volumetric flask and pipette. I want to dilute the acid to 0.1 moles, so I pipette 25.0cm3 of HCl from the original bottle and place it ...

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