oxidation and reduction

• What does redox involve?

  Electron transfer
• What is oxidation?

  Electron loss
• What is reduction?

  Electron gain
• What are redox reactions?

  • Processes where oxidation and reduction occur simultaneously
  • Referred to collectively as "redox reactions"
• What does an oxidising agent do?

  Accepts electrons and undergoes reduction
• What does a reducing agent do?

  Donates electrons and undergoes oxidation
• In the reaction between sodium and chlorine, what happens to sodium?

  Sodium is oxidised by losing electrons
• In the reaction between sodium and chlorine, what happens to chlorine?

  Chlorine is reduced by gaining electrons
• How do oxidation numbers change in redox reactions?

  Increase by 1 for every electron lost
• How do oxidation numbers change for electrons gained?

  Decrease by 1 for every electron gained
• How can you determine if a redox reaction has occurred?

  • Compare oxidation numbers before and after
  • Increase indicates oxidation
  • Decrease indicates reduction
• In the reaction Na(s) + 1⁄2Cl2(g) ➔ NaCl(s), what happens to sodium's oxidation number?

  It increases from 0 to +1
• In the reaction Na(s) + 1⁄2Cl2(g) ➔ NaCl(s), what happens to chlorine's oxidation number?

  It decreases from 0 to -1
• What does the mnemonic OILRIG stand for?

  • Oxidation Is Loss
  • Reduction Is Gain
• What occurs in a redox reaction between metals and acids?

  • Metal atoms lose electrons (oxidised)
  • Hydrogen ions gain electrons (reduced)
• In the reaction Mg(s) + 2HCl(aq) ➔ MgCl2(aq) + H2(g), what happens to magnesium?

  It is oxidised from 0 to +2
• In the reaction Mg(s) + 2HCl(aq) ➔ MgCl2(aq) + H2(g), what happens to hydrogen ions?

  They are reduced from +1 to 0
• What happens to chloride ions in the reaction between magnesium and hydrochloric acid?

  They remain unchanged and act as spectator ions
• What is the ionic equation for the reaction Mg(s) + 2H+(aq) ➔ Mg2+(aq) + H2(g)?


  Mg(s) + 2H+(aq) ➔ Mg2+(aq) + H2(g)