17 Redox Reaction Summary PDF

redox reaction Potassium Permanganate - oxidising agent Ammonium Iron(II) Sulfate - primary standard contains Mn in the (+7) oxidation state. To prevent the iron(II) in the solution from In acidic conditions, Mn is reduced reacting with the air to form iron(III) dilute completely (+2). sulphuric aci...

redox reaction Potassium Permanganate - oxidising agent Ammonium Iron(II) Sulfate - primary standard contains Mn in the (+7) oxidation state. To prevent the iron(II) in the solution from In acidic conditions, Mn is reduced reacting with the air to form iron(III) dilute completely (+2). sulphuric acid is added. However if acidic conditions are not used during the titration, an intermediate oxidation state will be reached (+4). To prevent this from happening dilute sulphuric acid is added to the KMnO4 solution. Oxidation States: Mn(+7) purple -> Mn(+4) Brown -> Mn(+2) colourless Potassium Permanganate vs. Ammonium Iron(II) Titration MnO₄- (aq) 5Fe 2+ (aq) + 8H + (aq) → Mn2+ + 5Fe3+ (aq) + 4H₂O (l) When adding any coloured solution such as KMnO4 to the burette the volume readings are taken from the top of the meniscus. Colourless -> persisting pale pink colour. Ratio: MnO₄- (aq) + 5Fe 2+(aq) 1 : 5 0.0005 : 0.0025 moles redox reaction Potassium Permanganate vs. Iron tablet titration Iron tablets are taken to prevent anaemia. Dilute H2SO4 added to prevent Fe(2+) being oxidised to Fe(3+) by air and to ensure complete reduction of Mn Colourless -> persisting pale pink colour. Steps to Solve Calculations: 1. Write out conclusion of titration. 2. Get moles of iron solution in titration. 3. Convert to moles 4. Use moles x Mr = mass to get the total mass of iron. 5. Find the mass of iron/ tablet. 6. Find % Iodine vs. Thiosulphate Titration Iodine is the oxidising agent. DI water must be used during this experiment as tap water contains chloride ions - These Cl- ions would displace iodine from iodine solutions thereby giving an inaccurate result. Iodine Solution(in conical flask) contains : potassium iodate (KIO₃), Excess dilute sulphuric acid, Excess potassium iodide (KI) The iodine is liberated from the potassium iodate (KIO3) solution, & a red-brown solution forms. Excess potassium iodide is used for a number of reasons: To ensure all of the I₂ ions from the potassium iodate are released. KI acts to keep the iodine that is formed in the reaction in solution. Add Starch Indicator when straw yellow colour detected. Colour Change : Red/Brown → Straw Yellow → Blue/Black → Colourless redox reaction % hypochlorite in bleach The hypochlorite ion (OCl-) is the active ingredient in bleaches. Because chlorine is higher in the halogen group it is a stronger oxidising agent & displaces iodine. I₂ + 2S₂O₃2- → S₄O₆2- + 2I- Colour Change : Add Starch Indicator when straw yellow colour detected. Red/Brown -> Straw Yellow - >Blue/Black -> Colourless