Redox

• What are the three definitions of oxidation and reduction used in chemistry?

  Processes that involve electron transfer
• What does the acronym "Oil Rig" help remember?

  • Oxidation is loss of electrons
  • Reduction is gain of electrons
• What is the oxidation state of an atom?

  The charge if bonding were ionic
• Why are oxidation states used in chemistry?

  To determine if oxidation or reduction occurred
• What is an oxidising agent?

  A substance that oxidises another atom
• What happens to an oxidising agent during a reaction?

  It gets reduced by gaining electrons
• What is a reducing agent?

  A substance that reduces another atom
• What happens to a reducing agent during a reaction?

  It gets oxidised by losing electrons
• What is required for a reaction to be classified as a redox reaction?

  Both an oxidising and reducing agent must be present
• How are oxidation states represented according to IUPAC?

  By Roman numerals
• Why are Roman numerals used for transition metals?

  To distinguish between different oxidation states
• What is the oxidation state of Fe in FeO?

  +2
• What is the oxidation state of Cl in HClO?

  +7
• What is the oxidation state of N in NO?

  +4
• What is the oxidation state of sulfur in S$_4$O$_6$?


  +2.5, but not a valid state
• Can oxidation states be fractions?

  No, only single atoms have integer states
• What is reduction in terms of electron transfer?

  Gain of electrons
• What does reduction cause in terms of oxidation number?

  It causes a decrease in oxidation number
• What are the types of reduction processes?

  • Loss of oxygen
  • Gain of hydrogen
  • Gain of electrons
• What happens in a redox reaction?

  • Oxidation and reduction occur simultaneously
  • One species is oxidised while another is reduced
• In the reaction Na + Cl → NaCl, which species is oxidised?

  Cl, as its oxidation state increases
• In the reaction Mg + Fe → Mg + Fe, which species is reduced?

  Fe, as its oxidation state decreases
• In the reaction CO + AgO → 2Ag + CO, which species is oxidised?

  CO, as its oxidation state increases
• What is the oxidation state of Na in NaCl?

  +1
• What is the oxidation state of Cl in NaCl?

  -1
• What is the oxidation state of H in H2O?

  +1
• What is the oxidation state of O in H2O?

  -2
• What is the oxidation state of S in SO2?

  +4
• What is the oxidation state of P in PO4^3-?

  +5
• What is the oxidation state of Al in AlCl3?

  +3
• What is the oxidation state of K in K2SO4?

  +1
• What is the oxidation state of Ca in CaCO3?

  +2
• What is the oxidation state of N in NH4+?

  -3
• What is the oxidation state of Br in Br2?

  0
• What is the oxidation state of I in I2?

  0
• What is the oxidation state of He?

  0
• What is the oxidation state of noble gases?

  0
• What is the oxidation state of transition metals?

  Varies, often +2 or +3
• What is the oxidation state of Li in Li2O?

  +1
• What is the oxidation state of Mg in MgO?

  +2