Test Objectives: Redox

  • define oxidation
  • know that oxidation is losing electrons
  • define reduction
  • know that reduction is gaining electrons
  • know the memory aid OILRIG and how to use it
  • assign oxidation numbers to each element in a compound or a polyatomic ion
  • know the 8 rules for assigning oxidation numbers
  • be able to identify if a reaction is a redox reaction
  • be able to determine;
  • what is being oxidized
  • what is being reduced
  • what is the oxidizing agent
  • what is the reducing agent
  • be able to correctly write & balance equations for the oxidation half reaction and the reduction half reaction in a redox reaction
  • know that electrical charge & mass must be conserved
  • be able to recognize an improperly balanced half cell reaction
  • be able to balance a redox equation by:
  • balancing electrons lost and electrons gained
  • balancing the atoms in the equation
  • be able to identify single replacement reactions be able to use table J to predict whether a given reaction will or will not occur
  • know that there are two types of electrochemical cells: Voltaic (or Galvanic) and electrolytic
  • voltaic cells arebatteries/electrolytic cells are plating cells
  • know that NYS Regents only refers to voltaic cells as “electrochemical” cells
  • know that voltaic cells are spontaneous and electrolytic cells are non-spontaneous
  • voltaic cells are exothermic; electrolytic cells are endothermic
  • voltaic cells produce electricity; electrolytic cells require an external source of electricity to work
  • be able to describe the differences between a voltaic cell & an electrolytic cell
  • given two metals & using table J be able to draw and label all the components for a given voltaic cell including:
  • both half cells
  • salt bridge (including direction of positive ion flow)
  • wire (including direction of electron flow)
  • cathode, anode (including which electrode is positive & which electrode is negative)
  • know which electrode increases in mass & which electrode decreases in mass
  • know at which electrode oxidation occurs and at which electrode reduction occurs (use table J )
  • know that in a voltaic cell as the redox reaction occurs:
  • the cathode (+) loses mass while the cathode solution concentration increases
  • the anode (-) gains mass while the anode solution concentration decreases
  • be able to explain the purpose of a salt bridge
  • know that in an electrolytic cell electricity is used to force a non-spontaneous reaction to occur
  • know that there are two types: fused salt cell & an electroplating cell
  • be able to draw and label all the components of an electrolytic cell:
  • the anode (+) & the cathode (-)
  • direction of electron flow
  • chemical components
  • be able to write the oxidation half reaction & the reduction half reaction
  • know that reduction still occurs at the cathode & oxidation still occurs at the anode
  • know that the “polarity” of the anode & cathode in an electrolytic cell is opposite that of a voltaic cell
  • know these differences between voltaic & electrolytic cells
  • voltaic:
  • redox reaction is spontaneous & exothermic
  • anode is negative , cathode is positive
  • electrolytic:
  • redox reaction is non-spontaneous & endothermic
  • anode is positive, cathode is negative
  • know these similarities between voltaic & electrolytic cells
  • both use redox reactions
  • anode is site of oxidation
  • cathode is site of reduction
  • electrons flow through the wire from the anode to the cathode