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Titration To Determine the Concentration of a Solution of Potassium Maganate.

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Introduction

TITRATION TO DETERMINE THE CONCENTRATION OF A SOLUTION OF POTASSIUM MAGANATE. Introduction The volume of potassium manganate v11 needed to neutralize the iron 11. You simply titrate the potassium manganate v11against the solution of iron 11and acid with a known concentration. Then when you have calculated the concentration of the acid you can use it in turn as a standard solution, to find the concentration of the solution of alkali. (Acids are substances which donate protons and the bases are substances which accept them) MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O (Purple) (H2So4) (Colourless) (Water) Reduction Mno4- , Mn+, Mn+7. Oxidation Fe2+ --> Fe3+ + 1e- The electron transfer must be the same... 5Fe2+ --> 5Fe3+ + 5e- Safety The sulphuric acid is corrosive. The potassium manganate is strongly oxidising. At all times through the experiment you must wear eye protection and lab coats. ...read more.

Middle

Rinse the wall of the reactor before the end point. Stop adding acid when a single drop turns the solution colourless. One drop accuracy. Record the new level of acid in the burette. Calculate the volume of acid used. Carry out four titrations, one trial and three accurate. Give your answer to 2 decimal places. Results Titrations Initial reading Final reading volume used cm3 1 0.00 28.55 28.55 2 0.00 28.40 28.40 3 0.00 28.55 28.55 4 0.00 28.45 28.45 Calculations Average volume of potassium manganate v11 used, from three accurate titrations: 28.40 + 28.55 + 28.45 = 28.47 cm3 Moles of Fe2+ = Concentration * volume in dm3 = 0.1 * 0.025 = 0.0025 moles From the equation MnO4- + 8H+ + 5e- --> Mn2+ + 4H2O 5 moles of Fe 11 = 1 moles of MnO4 Concentration = moles / volume 0.0125 moles of Fe 11 = 0.0025 moles of MnO4 Concentration of MnO4 = moles / ...read more.

Conclusion

We could not collect all the solutions no matter how hard we tried. Due to equipment error. Instrument accuracy/ lowest reading * 100 = ans 0.05/ 28.40 * 100 = 0.17% For the burette. This shows that the equipment are not absolute accurate. Another factor could have been the air around us. Or standing near the window and the outside temperature could have its effect. Other instruments could be used which have a better accuracy point. More sophisticated measuring equipment could also be another point to notice. Conclusion The morality of the potassium manganate v11 was 0.087 moldm3. The results were close together and the indicator changed quickly at the end point. If you were to repeat this experiment you could make it better by using a different indicator e.g. methyl orange, indicators are weak acids, where the acid and its conjugate bases are different colours. The ph of the indicators changes over 2 units. Or using a different concentration of iron II. 02/05/2007 AKRAM ALI ...read more.

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