chap 7 redox chemistry

• when a substance gain oxygen atoms, it has oxidised
• when a substance lose hydrogen atoms, it has oxidised
• when oxidation state of atom increased, it has oxidised
• when a substance gains hydrogen atoms, it has reduced
• when a substance lose oxygen atoms, it has reduced
• when oxidation state of atom decreased, it has reduced
• oxidation state of element is 0
• oxidation state of hydrogen in compounds is +1
• oxidation state of oxygen in compounds is -2
• oxidation state of metals in compounds is their ionic charge
• total oxidation state of a compounds is 0
• when substance loses electrons, is has oxidised
• when substance gains electrons, it has reduced
• what is an oxidising agent?

  it is a substance that oxidises another substance and is itself reduced in the process
• what is an reducing agent?

  it is a substance that reduces another substance and is itself oxidised in the process
• test for oxidising agent

  add the solution into potassium iodide solution, and it should turn from colourless to brown
• test for reducing agent

  add solution into acidified potassium manganate (VII) solution, and it should turn from purple to colourless or pale pink
• disproportionation reaction is a redox reaction where the same element is both oxidised and reduced simultaneously
• name a reducing agent

  potassium iodide
• name oxidising agent

  acidified potassium manganate (VII) or acidified potassium dichromate (VI)