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REDOX TITRATION AND ITS APPLICATION

REDOX TITRATION AND ITS APPLICATION. REDOX TITRATION. Permanganometry Dichromatometry Cerimetry Iodo-iodimetry Bromatometry. Permanganometry. Permanganometry : redox titration on using KMnO 4 as a titrant . Potassium permanganate: *) strong oxidator

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REDOX TITRATION AND ITS APPLICATION

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  1. REDOX TITRATION AND ITS APPLICATION

  2. REDOX TITRATION Permanganometry Dichromatometry Cerimetry Iodo-iodimetry Bromatometry

  3. Permanganometry

  4. Permanganometry: redox titration on using KMnO4 as a titrant. • Potassium permanganate: • *) strong oxidator *) can easily find, cheap *) no need indicator to observe end point. *) purple color *) can be oxidized by light • use of KMnO4 in daily life: anti bacteria (PK)

  5. Oxidation number of Manganese: +2, +3+, +4, +6, dan +7. MnO4- + e-  MnO42- MnO4- + 4H+ + 3e-  MnO2 + 2H2O MnO4- + 8H+ + 4e-  Mn3+ + 4H2O MnO4- + 8H+ + 5e-  Mn2+ + 4H2O • Common reaction in lab: MnO4- + 8H+ + 5e- Mn2+ + 4H2O • Acid can be used: dilute H2SO4 • reaction need to be heat and catalyst

  6. Standard primary for KMnO4: 1. Arsen (III) Oksida, As2O32. Sodium Oxalic Na2C2O4

  7. REACTIONS: • 5 C2O42- + 2 MnO4- + 16 H+ 2 Mn2+ • + 10 CO2+ 8H2O 5 HAsO2 + 2 MnO4- + 6 H+ + 2 H2O  2 Mn2+ + 5 H3AsO4

  8. The use of Permanganometry: a. Determination of Iron in minerals : solve the minerals in acid (HCl), ttrate with permanganate 5Fe2+ + MnO4- + 8H+ -- 5Fe3+ + Mn2+ + 4H2O b. Determination of Hydrogen peroxyde 2 MnO4- + 5 H2O2 + 6 H+  2 Mn2+ + 5 O2(g) + 8 H2O Hydrogen peroxyde in daily life: ear drops medicine (3%)

  9. Standarisasi larutan permanganat • Larutan kalium permanganat bukan larutan standar primer karena sukar mendapatkan yang murni, selain itu sifatnya mudahterurai oleh cahaya, suhu tinggi, asam/basa dan zat organik • Larutan permanganat dapat distandarisasi antara lain dengan: • Arsen (III) Oksida • Natrium Oksalat

  10. Exercise-1 • Iron (II) is titrated with potassium permanganate 0,0206 M, in acid media. It is used 40,20 mL of KMnO4 solution to react with. Determine mg of iron in the solution.

  11. Solution: • In acid solution: MnO4- + 8H+ + 5e - Mn2+ + 4H2O X1 Fe2+ -- Fe3+ + e X5 • MnO4- + 8H+ + 5Fe2+- Mn2+ + 4H2O + 5Fe3+ • In equivalent point: Mol KMnO4 = M.V

  12. Mol KMnO4 = M.V = 0,0206 M x 40,2 mL = 0,828 mmol • 5 mol Fe  1 mol KMnO4  mol Fe yang diperlukan = 5 x 0,828 mmol = 4,14 mmol • Fe needed: = 4,14 mmolAr.Fe. = 231,8 mgram

  13. Exercise - 2 0,2121 gram sampel natrium oksalat murni dititrasi dengan 43,31 ml kalium permanganat. Hitunglah normalitas kalium permanganat

  14. Dichromatometry

  15. Dichromate as strong oxidator (but less than permanganate) • Ion dichromate is reduced into Cr3+ ion (green color). • Cheap, easily found in pure grade • Cr2O72- + 14H+ + 6e- 2Cr3+ + 7H2O

  16. Application • Determine Fe(II) in acidic (HCl) media. • Write the complete reaction

  17. TITRATION WITH IODIUM

  18. Iodimetri (cara langsung) • adalah titrasi yang dilakukan langsung dengan larutan standar iodium sebagai pengoksid, dilakukan dalam suasana netral atau sedikit asam. • Beberapa Penggunaan Iodimetri

  19. Some reactions • Arsen (III) HAsO2 + I2 + 2H2O - H3AsO4 + 2H+ + 2I- • Ferosianida 2Fe(CN)64- + I22Fe(CN)63- + 2I- • Belerang (sulfida) H2S + I2 - 2H+ + 2I- + S • Belerang (sulfit) H2SO3 + I2 + H2O - H2SO4 + 2H+ + 2I- • Tiosulfat 2S2O32- + I2 - S4O62- + 2I-

  20. Some reactions: • Bromate BrO3- + 6H+ + 6I- - Br- + 3I2 + 3H2O • Klorine CI2 + 2I- - 2CI- + I2 • copper (II) 2Cu2+ + 4I-- 2CuI(s) + I2 • Dichromate Cr2O72- + 6I- + 14H+ 2Cr3+ + 3I2 + 7H2O • Hydrogen peroxyde H2O2 + 2H+ + 2I- I2 + 2H2O

  21. Natrium tiosulfat umumnya dibeli sebagai pentrahidrat. Na2S2O3.5H2O, dan larutan-larutannya distandarisasi oleh standar primer. • Larutan tiosulfat tidak stabil pada jangka waktu yang lama, sehingga boraks atau natrium karbonat seringkali ditambahkan sebagai bahan pengawet. Selain itu larutan ini sifatnya tidak stabil terhadap oksidasi dari udara, asam dan adanya bakteri pemakan belerang yang terdapat dalam pelarut. • Larutan Na2S2O3 harus disimpan pada tempat yang tidak kena langsung matahari.

  22. Example: • Sodium thiosulphate is standardized on using methods : 0,1210 g of KIO3 is dissolved in water (214,00 g/mol) , the excess of KI is added and acidified with HCl. The free Iodine need 41,64 mL of thiosulphate solution to reacted. Ditermine the molarity of Na2S2O3.

  23. Solution: • mmol Na2S2O3 = 0,1210 g KIO3 x …….. = 3,3925 mmol Na2S2O3 • Molarity of sodium thiosulphate: • = 0,0815 M

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