Back Titration Lab Report. In my experiment, I hoped to find the amount of calcium carbonate in some mineral limestone using the back titration method

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Back Titration Lab Report

Aim: 

Determining the percentage purity of calcium carbonate in a sample of limestone.

Introduction:

In my experiment, I hoped to find the amount of calcium carbonate in some mineral limestone using the back titration method

The equation of the reaction is as follows:

2HCl + CaCO3 → CaCl2 + CO2 + H2O

As not all the acid will be used up in the above reaction, I plan to obtain the amount of acid not used up and consequently the amount of calcium carbonate in the limestone, by titrating it with known sodium hydroxide solution. The equation of the reaction is as follows:

HCl + NaOH → NaCl + H2O

Apparatus:

The equipment and reagents that I used are as follows:

250 cm3 beaker

Electronic balance (± 0.01 g)

250 cm3 volumetric flask (± 0.2 cm3)

50.0 cm3 burette (± 0.05 cm3)

25. 0 cm3 pipette (± 0.1 cm3)

3 x conical flasks

Clamp and retort stand

1.0 mol dm-3 hydrochloric acid, HCL        

1.5 g of limestone

phenolphthalein  indicator

  1. mol dm-3 Sodium hydroxide, NaOH

        

 Method:          

When I had all this, I started my investigation by weighing 1.5 g of limestone on the electric balance. After obtaining the weighed crystals I dissolved them with 1.0 mol dm-3 hydrochloric acid, in the beaker provided and stirred the mixture till bubbling stopped. I then added the solution into the volumetric flask and topped it with distilled water till I reached the 250 cm3 mark.

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I than mounted the burette on the retort stand, and filled it with the 0.10 mol dm-3 Sodium Hydroxide solution up to the 50 cm3 mark.

After doing all this, I titrated the solution of the limestone against the base from the burette, until the colour of the solution in the conical flask just turned pink. I repeated the procedure to obtain 3 sets of readings and will take the average value as my result.

Data processing and presentation:

With all the above processes being done, I wrote down the values which I obtained in the raw data ...

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This is a four star piece of work with excellent scientific knowledge of molar calculations and demonstrated great skill in their work. A clear, concise piece of work but they could have put more into the introduction and conclusion.