Aim; 1)To prepare a standard potassium dichromate solution 2)To standardize the ammonium iron(II) sulphate solution 3)To determine the given unknown potassium permanganate solution 4)To estimate the concentration of hydrogen peroxide

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Course Code: 13554/Y1

Student Name: Chow Man Chung

             Lam Kwok Kei

             Lee Long Sing

             Chan Ka Chun

Date performed: 29th September, 2010

Experiment 4: Reduction Titration I

Objective:

  1. To prepare a standard potassium dichromate solution
  2. To standardize the ammonium iron(II) sulphate solution
  3. To determine the given unknown potassium permanganate solution
  4. To estimate the concentration of hydrogen peroxide

Apparatus & equipments used:

  1. Burette, 50mL capacity
  2. Bulb pipette, 25mL capacity
  3. Volumetric flask, 250mL capacity

Chemicals used:

  1. Potassium dichromate solid
  2. Potassium permanganate solution, 0.02M
  3. Dilute sulphuric acid solution, 2.5M
  4. Hydrogen peroxide sample solution
  5. Fe2+ Solution, approx. 0.1M
  6. N-phenylanthranilic acid indicator
  7. Barium diphenylamine sulphonate indicator, 1% aq.

Results and Data Treatment:

Weighting Data:

Mass of vial: 6.3545g

Mass of vial and Potassium dichromate: 7.5975g

Mass of Potassium dichromate: 1.2430g

Resulting Potassium dichromate solution made up to: 250.0cm3

Titration I: Standardization of iron(II) solution

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Titrant (in burette): Potassium Dichromate

Titrate (in conical flask): 25.0cm3 of Fe2+ Solution

Indicator used: N-phenylanthranilic acid indicator

Colour of indicator changed from: Orange to Purple

Average volume: 24.20 cm3

Calculation:

Number of mole of Kr2Cr2O7 = 1.2430 / [(7)(15.9994)+(2)(51.9961)+(2)(39.0983)]

                         = 0.004225

 Cr2O72- : Fe2+ = 1 : 6

 Number of mole of Fe2+ = [(0.004225)(6)](25/250)

                       = 0.002535

Molarity of Fe2+ = 0.0002535 / (24.2/1000)

              = 0.1047

        ...

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