concntraion of calium hydroxide

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To determine the concentration of a calcium hydroxide solution


 Our aim is to use a standard solution of hydrochloric acid to find the concentration of limewater (Calcium hydroxide).


Choosing a suitable indicator is important, I had to be extremely careful with this, I have chosen to use the indicator methyl orange. The limewater used will be a relatively weak base so it will be appropriate for using methyl orange and the acid that I am using is strong.

Safety notes: 

  • Safety goggles must be worn at all times whilst carrying out this experiment.

Hydrochloric acid:

  • Contact with the eyes or skin can cause serious permanent damage.  When in contact with the eyes immediately rinse the eye with plenty of water and call for medical help. 
  • If in contact with skin rinse thoroughly and if redness on skin occurs call for medical help.

Calcium hydroxide:

  • Powder may irritate the eyes. So if contact with eyes immediately rinsed the eyes with plenty of water, if irritation persists then calls for medical help. Since we are provided with a solution there is no particular danger.
  • When in contact with skin wash of with soap and water.
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  • 250cm3 volumetric flask
  • 5cm3 graduated pipette
  • burette
  • pipette filler
  • white tile
  • clamp and stand
  • funnel
  • conical flask 250cm3
  • 100cm3 beaker

Balanced equation:

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


Firstly I will calculate the approximate concentration of the calcium hydroxide in mol dm-3

Moldm-3 = gdm-3/Mr = 1/74.1 = 0.014 (3.d.p)

Now I will use the balanced equation to work out the approximate concentration of HCl needed. To work this I would need to know ...

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Here's what a star student thought of this essay


Punctuation, grammar and spelling all done to a good level. The candidate lays the essay out in a good format. The referencing could have been done a bit tidier by using the harvard referencing format.

The candidate only explains weakly why they will use the methyl orange indicator. To improve they should compare other indicators and explain their choice with its properties for thoroughly for the suitability for the experiment to go ahead. They explain the safety elements behind the experiment well. The equation used is in a correct format with correct balancing used. The dilution and titration methods used are calculated accurately and explained well. Decimal places lack consistency in one or two places and this could affect the accuracy of the results.

The focus of the question is done well. The candidate provides accurate worked out solutions and explains how to dilute the HCl to the desired concentration. The main thing missing is the ending of the experiment which is not included in this format.