• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

determination of the percentage of oxalate in iron (II) oxalate by redox titration

Extracts from this document...

Introduction

F.6A Lam Pik Sum (10) Title: determination of the percentage of oxalate in iron (II) oxalate by redox titration Date: 31/10/2008 Objective: to find out the percentage of oxalate in iron (II) oxalate by redox titration. Introduction Potassium manganate (VII) is not suitable for use as a primary standard as its solution decimoises in solution, especially in sunlight, and readuky oxidizes organic matter. Moreover, brown deposits of manganese (IV) oxide are often present in its solution. In fact, potassium manganate (VII), being not a primary standard, is usually standardized by standard solution of sodium thiosulphate. Permanganate ion, MnO4(aq), is a strong oxidant. Since permanganate ion is intensely coloured and its reduction product, Mn2+(aq), is almost colourless, a self-indicating titration is possible. The addition of the first drop of permanganate solution in excess imparts a pink colour to the solution. Potassium manganate(VII) reacts quantitatively with many reducing agents. Oxalates are readily determined by titration with standard potassium manganate (VII) in warm acidic solution: C2O42- � 2CO2 + 2e- In strongly acidic medium, permanganate undergoes a 5 electrons reduction to manganese(II) ion: MnO4(aq) + 8H+(aq) + 5e- � Mn2+(aq) + 4H2O(aq) Potassium permanganate does not oxides oxalates in cold solution. A temperature of about 70�C is necessary to cause the reaction to occur rapidly. If coloured or oxidized cations are present, the procedure will be more complicated. ...read more.

Middle

x 100% = 61.2% Mass of FeC2O4 in the sample = 88 x 0.014467125 = 1.273107g Calculated percentage of oxalate in the sample = (1.273107 � 2.632) x 100% = 48.4% The chemical formula of the hydrated iron (II) oxalate We assume all the impurity in the sample are water of crystallization, then the water of crystallization by mass in the compound is 21% and the chemical formula of hydrated iron (II) oxalate is known to be FeC2O4?xH2O Relative formula mass of FeC2O4?xH2O = 55.8 +12x2 + 16x4+ (1x2 +16)x = 143.8 + 18x Relative molecular mass of water of crystallization = 18x 18x � (143.8 + 18x) = 21 � 100 1800x = 3019.8 + 378x 1422x = 3019.8 x = 2.124 �2 Therefore, the chemical formula of the hydrated iron (II) oxalate is FeC2O4?2H2O. Conclusion The percentage of oxalate in iron (II) oxalate is 48.4% which is smaller than the predicted one. Discussion Precaution 1) Handle potassium permanganate with great care because it is toxic and irritation to skin 2) Handle manganese (IV) oxide with great care because it can cause serious eye injury, is a skin and inhalation irritant, and can be fatal if swallowed Sources of error 1) KMnO4 is too reactive that light may induce the decomposition of KMnO4. It may lead to the error in accurate determination of the concentration of oxalate. ...read more.

Conclusion

In the initial stages of the titration, only a small amount of Mn2+ is formed, therefore the reaction is slow and the Mn2+ is discharged at a slow rate and the colour of Mn2+ is covered by the green Fe2+. 7) You are given a standard solution of potassium iodate, some solid potassium iodide, a bottle of dilute sulphuric acid and some starch indicator. Describe briefly how you could standardize a solution of sodium thiosulphate. You may assume that all common titration apparatus is available. We can standardize sodium thiosulphate solution through titration of iodine with thiosulphate, therefore we need to prepare a standard iodine solution. A standard iodine solution cannot be prepared directly by accurately weighing a certain amount of iodine, but it can be prepared by dissolving a known amount of pure potassium iodate solid into an acidic medium containing excess iodide. We first dissolve weighed amount of KI into dilute sulphuric acid. The number of mole of it should be at least 5 times that of potassium iodate. After adding potassium iodate solution into acidified KI, iodine would be formed. Just use a small portion of the mixture and titrate with thiosulphate solution until the brown color nearly fade, then add starch solution and continue to titrate until the mixture becomes colourless. If Potassium iodate is in excess rather than KI, a slight addtion of KI to the resulting mixture would form a brown to dark brown mixture indicating that I2 is formed. End of Report ?? ?? ?? ?? 1 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Inorganic Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Inorganic Chemistry essays

  1. Peer reviewed

    Determining the concentration of acid in a given solution

    5 star(s)

    even concentration you throughout If the volumetric flask wasn't tipped then the concentration of the sodium carbonate would be higher at the bottom of the flask. When the solution is taken out of the volumetric flask, the pipette usually reaches to the bottom of volumetric flask.

  2. effects Concentration and Temperature on the Rate of Reaction

    e = mathematical value similar to pi (has a value of 2.71828) Ea = the activation enthalpy R = the gas constant (has a value of 8.31 J K-1 mol-1 T = temperature (in Kelvin) k = Ae-Ea/RT This equation can be rearranged by taking the log (to the base e)

  1. Chem Lab report. Objective: To determine the concentration of potassium manganate(VII) solution using ...

    solution. ? no. of moles ofMnO4- = no. of moles of KMnO4 So the molarity of the potassium manganate(VII) solution Procedures: 1. The mass of solid ethanedioic acid (C2H2O4?2H2O) required to prepare the standard ethanedioic acid was weighed. 2. All solid ethanedioic acid was dissolved in a beaker with a suitable amount of deionized water and the mixture was stirred.

  2. THERMOMETRIC TITRATION

    Assume that the specific heat capacity of the solution is the same as water, 4.18 KJKg-1K- . Ans: ? H for HCL: ?H = MC? T Volume is 71cm3 = 71/1000 = 0.071 dm3 Temperature = recorded from the graph (final - initial). ?H = (volume of NaOH + HCl)

  1. Lab report Determination of Enthalpy Change of Neutralization

    -51.3KJ mol-1 Reaction 2: Mass of the solution = (25 + 25) /1000 = 0.05 Kg Heat given out = (0.05 * 4200 + (3/29 * 0.02073 + 3/26 * 0.02234) * 840) * 12.8 = 2738.772826 J HCl (aq)

  2. Determination of Chemical Oxygen Demand (COD) of a Given Sample of Waste Water

    FAS remained in such form, and appeared as reddish brown colour due to the presence of Fe2+ ions. In the process of oxidizing the organic substances found in the water sample, potassium dichromate is reduced, forming Cr3+. The amount of Cr3+ is determined after oxidization is complete, and is used

  1. Determination of the formula of hydrated Iron (II) Sulphate crystals (FeSO4xH2O)

    Invert the volumetric flask several times to ensure that the solution is evenly mixed. 2. Using a pipette filler, pipette 25.0cm3 of the solution of iron(II) sulphate into a conical flask and add approximately 20.0cm3 of the 1 mol dm-3 H2SO4 (aq) solution provided. 3. Titrate the acidified Fe2+ (aq)

  2. Aim: To determine the activation energy of the reaction between bromide ion and bromate(V) ...

    Explain why the reaction rate can be affected by temperature. By the Arrhenius equation, where k is the rate constant of the reaction, A is the constant which is independent of temperature, e is the base of natural logarithm, Ea is the activation energy of the reaction in J mol-1, R is the ideal gas constant (i.e.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work