intro

• reactions can be sorted into two groups: a proton transfer or an electron transfer

  • H+ (acids and bases)
  • e- (redox)
• an electrochemical reaction occurs when there is a transfer of electrons (e-)

  • chemical energy -> electrical energy (ex. batteries)
  • something gains electrons (reduced) and something loses electrons (oxidizes)
• operational definition - reduction:

  • rock ore -> atomic metal
  • smelt, roast, heat
  • ex. CuS + H2 -> Cu + H2S
  • Cu2+ + 2e- -> Cu
  • H2 is a reducing agent; Cu was reduced
• theoretical definition - reduction:

  • a chemical process involving the gain of e-
  • becomes more negative
  • decrease in oxidation #
• reducing agent - promotes reduction of another substance by donating its e-
• Operational definition - oxidation:

  • a substance reacts with O2
  • rust, corrosion, combustion
• theoretical definition - oxidation:

  • a chemical process involving the loss of e-
  • increase in oxidation state
• oxidation agent - an entity that promotes oxidation of another substance by taking e-
• 1/2 reactions:

  • redox rxns must have an equal number of e- transferred

  1. write net ionic equation
  2. write and label 2 half rxns; balance e- and add togeather
  3. LEO says GER; OAR
• LEO says GER:

  • Losing Electrons Oxidation
  • Gaining Electrons Reduction

  OAR: (up and down)

  O - oxidized

  A - agent

  R -reduction