Oxidation & Reduction Summary PDF

Oxidation & Reduction Oxidation is the loss of electrons Bromine water added to potassium iodide Reduction is the gain of electrons solution: Initial Colour: Memory aid: OILRIG Colourless Reaction: An oxidising agent is a substance that allows Red - Brown (colour of Final Colour: oxidation to happen...

Oxidation & Reduction Oxidation is the loss of electrons Bromine water added to potassium iodide Reduction is the gain of electrons solution: Initial Colour: Memory aid: OILRIG Colourless Reaction: An oxidising agent is a substance that allows Red - Brown (colour of Final Colour: oxidation to happen by gaining electrons liberated iodine) itself. anion tests Common oxidising agents include: Use: 1. Oxygen Combustion 2.Potassium Permanganate Titrations 3. Sodium Dichromate Organic reactions 4. Hydrogen Peroxide Rates of reaction experiments A reducing agent is a substance that allows reduction by losing electrons itself. Halides are salt solutions containing a halogen Reaction of halogens with halides water added to Add BaCl₂ to a sulphite solution → Forms a white precipitate Add dilute HCl → White precipitate dissolves Chlorine is then added to the sulphite solution The sulphite is oxidised to sulfate All halogens are reducing agents. Chlorine TEST FOR SULFITES (to ensure no sulphates are present): TEST FOR SULFATES Add BaCl₂ to the sulfate potassium White ppc forms bromide solution Add dilute HCl Initial Colour: Colourless Reaction: Final Colour: Orange (colour of liberated bromine) Chlorine water added to potassium iodide solution: Initial Colour: TEST FOR Fe 2+ (to ensure no Fe3+ is present): Add 10 drops of NaOH Colourless A green ppc. indicates Fe 2+ ions are present Chlorine is then added to the Fe(II) solution Red - Brown (colour of Fe(II) is oxidised to Fe(III) Reaction: Final Colour: If white ppc does not dissolve then sulfates are present liberated iodine) Oxidation & Reduction TEST FOR Fe 3+ Add 10 drops of NaOH An orange-brown (rusty) ppc indicates Fe 3+ ions are present Test For Nitrates Add Iron II sulphate. add 5 drops of concentrated sulphuric acid down the side of the test tube. Result: A brown ring formed near the bottom of the test tube. Conclusion: The solution contained nitrate ions. anion tests Ion Add Result Add Result Chloride Silver Nitrate White Precipitate Ammonia Precipitate Dissolves Sulfate Barium Chloride White Precipitate Dil. HCl No Change Sulfite Barium Chloride White Precipitate Dil. HCl Precipitate Dissolves Carbonate Magnesium Sulfate White Precipitate Hydrogencarbonate Magnesium Sulfate No Change Boil Gently White Precipitate Brown Ring at junction Yellow Precipitate Nitrate Iron Sulfate No Change Conc. HCl (very carefully down inside) Phosphate Ammonium Molybdate No Change Conc. Nitric Acid