Titration KMnO4+ FeSO4 12/2/2013 At Alsadek Scientific Association Prepared by: Zainab Alfakih & Jinan Krayem Teacher: Dr. Hiba Nassar Contents Introduction2 Objectives3 Theoretical Study3 Definitions3 Derivations3 Equipment4 Setup5 Procedures5 Results6 Discussion7 Conclusion8 References9 I.
Introduction: Oxidation Reduction reactions are chemical reactions in which substances undergo changes in oxidation state. Oxidation is defined as the loss of electrons (or an increase in oxidation state) and reduction as the gain of electrons (or a decrease in oxidation state).In acid base titrations, equivalent amounts of acid and base must be used for exact neutralization at the titration endpoint. In oxidation-reduction reactions, there is a similar equivalence between oxidizing and reducing agents. In order for a redox reaction to be valid, it should be unique, complete spontaneous and rapid. In titration: * Reaction is unique.
The condition is indispensable to establish a relation between the amounts of matter of the reactants involved. * Reaction is complete. The reagents, which are introduced in stoichiometric proportions, should be completely consumed at equivalence.This is expressed by a difference in potentials of the two couples involved, ? E0, greater than 0. 3V.
* Reaction is spontaneous and rapid. Reactants should react spontaneously and instantaneously as soon as the mixed. II. Objectives: * To use a standardized acid solution to determine the concentration of a base solution. * To learn the technique of titration III.
Theoretical Study: 1) Definitions: a. Definition of titration: Volumetric titration consists of the addition of a determined volume of titrating solution with known concentration C1 to an exact volume of solution with unknown concentration C2 to be determined.Volumetric titration is based on a reaction, which occurs between the titrating solution (titrant) and the solution to be titrated (analyte). Redox reactions are used to realize such titrations. b. Definition of equivalence point: The equivalence point corresponds to the end point of titration reaction.
It is determined by a change of color in the reaction, the reactants have reacted in stoichiometric proportions. If either the titrant or analyte is colored, the equivalence point is evident from the disappearance of color as the reactants are consumed. 2) Derivations: a. Balanced redox equation: Fe2++8H++MnO4->5Fe3++Mn2++4H2O b. Concentration of H2SO4: Given: H2SO4M=98. 08 mol.
l-% by mass=98%d=1. 84 Kg. l-=1840g. l- %by mass=mH2SO4msolution? 100 %by mass=mH2SO4VsolutionmsolutionVsolution? 100 >%by mass=Cm? 100dsolution But: Cm=C? M >CH2SO4=%by mass? dsolution100? MH2SO4=98? 1840100? 98.
08=18. 38 mol. l- >H2SO4=18. 38 mol. l- c.
Dilution of H2SO4: Given: H2SO4C1=18. 38 mol. l-V1=?? H2SO4C2=1 mol. l-V2=100ml n1=n2 >C1? V1=C2? V2 >18. 30? V1=1? 100 >V1=5. 4ml d.
Mass of KMnO4 (titrant): Given: KMnO4V=100ml=0. 1Lm=0. 3g C KMnO4=n KMnO4V KMnO4=m KMnO4M KMnO4V KMnO4 But: MKMnO4=MK+MMn+4MO=39+54. +416=157.
9gmol >CKMnO4=0. 3157. 90. 1=0.
02molL e. Mass of FeSO4 (analyte): theoratical mFeSO4=4. 2g It is only used for the comparison at the end of the reaction. IV.
Equipment: * Burette * Pipet * Beaker * Erlenmeyer flask * Pipet bulb * Stand * Filter funnel * Distilled water * FeSO4 solution * KMnO4 solution Note: In order to get an exact and precise result of the titration, all glassware used in the titration should be cleaned with distilled water. All the equipment used should be kept in good state of cleanness. V. Setup: Figure 1: Experiment Setup. VI. Procedures: A.
Preparation of 0. g potassium permanganate: 1. Dissolve about 0. 3 g of KMnO4 in 250 mL of distilled water. 2.
Keep the solution at a gentle boil for about half hr. Figure 2: mass of KMnO4 B. Preparation of 4. 2g FeSO4.
5H2O: Dissolve 4. 2g FeSO4 in 25 ml of H2O and stir to mix very well. Figure 3: mass of FeSO4 C. Procedures of titration: 1. Clean the burette with distilled water, then open the tap to ill the with KMnO4 solution.
2. Prepare one mole of H2SO4 from stock of H2SO4 (98%) 3. Using a volumetric pipet, transfer 10 ml of Fe2+ solution into the flask 4. Add 3 to 5 ml of a concentrated acid solution 5.Add progressively the MnO4- solution from the buret safetly with continuous stirring till the persistence of a pink color (equivalence point). 6.
Record the volume of MnO4- added and make your calculations. VII. Results: Equation of the reaction: 5Fe2++8H++MnO4->5Fe3++Mn2++4H2O At equivalence point, the reaction is stoichiometric. At equivalence point, and according to stoichiometry: nFe2+5=nMnO4-1 * Dissociation equation of FeSO4: FeSO4>Fe2++SO42-. >nFeSO41=nFe2+1 * Dissociation equation of KMnO4: KMnO4>K++ MnO4-.
>nKMnO41=n MnO4-1 >nanalyteFeSO45=ntitrantKMnO41 >nanalyteFeSO4=5? ntitrantKMnO4 CFeSO4? VFeSO4=5? CKMnO4? VKMnO4 >CFeSO4=5? CKMnO4? VKMnO4VFeSO4 But: mFeSO4=nFeSO4? MFeSO4 and MFeSO4=151. 607gmol. Trials| VtitrantKMnO4 in L| CanalyteFeSO4 in molL| manalyteFeSO4 in g| 1| 13. 9| 1. 39| 2. 107| 2| 13.
3| 1. 33| 2. 016| Figure 4: volume of KMnO4 in the 2nd trial starting initially at 5 ml. VIII. Discussion: Each time the experiment is repeated, the value of the concentration of FeSO4 differs slightly. This difference is due to the accidental errors that happened upon observing the persistence of pink color and also the reading of the values of the volume of titrant.
So the average value of concentration of FeSO4 is: C = C1+C22 = 1. 36 molL The accidental error is: e = max {|C – C1|, |C – C2|} = 0. 03 Then C= C ± error = (1. 36 ± 0. 03) molL IX. Conclusion: After performing two experiments and studying their results to know the concentration of FeSO4, we figured out that C= (1.
36 ± 0. 03)molL. The concentration and mole of acid or base can be determined using titration process by a given value for one of the substances. X. References: * http://dwb.
unl. edu/calculators/activities/DiproticAcid. html * http://www. scribd. com/doc/20300492/Experiment-3-Acid-and-Base-Titration
