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Introduction to Chemistry: Oxidation-Reduction and Electrochemistry

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  • What is a fuel cell?
    A device that uses the electron-gaining tendency of oxygen and the electron-losing tendency of hydrogen to produce electricity by forcing electrons to move through a wire.
  • What is oxidation in terms of electrons?
    Oxidation is the loss of electrons.
  • What is reduction in terms of electrons?
    Reduction is the gain of electrons.
  • What does OIL RIG stand for in redox reactions?
    Oxidation Is Loss (of electrons); Reduction Is Gain (of electrons).
  • What is the role of a reducing agent?
    A reducing agent is the substance that loses electrons and causes another substance to be reduced.
  • What is the role of an oxidizing agent?
    An oxidizing agent is the substance that gains electrons and causes another substance to be oxidized.
  • How are oxidation states assigned?
    Oxidation states are assigned by giving all shared electrons to the most electronegative element and calculating a number called the oxidation state or oxidation number.
  • What is the oxidation state of an atom in its elemental form?
    The oxidation state of an atom in a free element is 0.
  • What is the oxidation state of a monoatomic ion?
    The oxidation state of a monoatomic ion is equal to its ionic charge.
  • What is the sum of oxidation states in a neutral molecule?
    The sum of the oxidation states of all atoms in a neutral molecule or formula unit is 0.
  • What is the sum of oxidation states in a polyatomic ion?
    The sum of the oxidation states of all atoms in a polyatomic ion equals the charge of the ion.
  • What oxidation states do Group 1 and Group 2 metals have in compounds?
    Group 1 metals have an oxidation state of +1, and Group 2 metals have an oxidation state of +2 in their compounds.
  • What is the oxidation state of fluorine in compounds?
    Fluorine has an oxidation state of -1 in its compounds.
  • What is the oxidation state of oxygen in most compounds?
    Oxygen usually has an oxidation state of -2 in compounds.
  • How can you identify which element is oxidized or reduced using oxidation states?
    The element whose oxidation state increases is oxidized, and the element whose oxidation state decreases is reduced.
  • What is the activity series of metals?
    A list of metals ordered by their tendency to lose electrons; metals at the top oxidize easily and are more reactive, while those at the bottom oxidize less easily.
  • How does the activity series predict spontaneous redox reactions?
    A metal higher in the activity series will spontaneously oxidize and reduce ions of a metal lower in the series, producing a spontaneous redox reaction.
  • What is a voltaic (galvanic) cell?
    An electrochemical cell that produces electrical current from a spontaneous redox reaction by separating oxidation and reduction half-reactions.
  • What are the anode and cathode in a voltaic cell?
    The anode is where oxidation occurs (negative sign), and the cathode is where reduction occurs (positive sign). Electrons flow from anode to cathode.
  • What is the function of a salt bridge in a voltaic cell?
    The salt bridge completes the circuit by allowing the flow of ions between the two half-cells, maintaining electrical neutrality.
  • What is voltage in a voltaic cell?
    Voltage, or potential difference, is the driving force that causes electrons to flow through a wire in a voltaic cell.
  • What happens in electrolysis?
    Electrical current is used to drive a nonspontaneous redox reaction in an electrolytic cell.
  • How can electrolysis be used to produce metals?
    Electrolysis reduces metal ions from metal oxides to pure metals, a nonspontaneous process requiring electrical energy.
  • What causes corrosion?
    Corrosion is the oxidation of metals, such as iron rusting, where iron is oxidized and oxygen is reduced.
  • How can corrosion be prevented?
    By keeping metals dry, coating them with paint or protective layers, or using a sacrificial anode made of a more reactive metal.
  • What is a sacrificial anode?
    A metal more reactive than iron that oxidizes in place of iron, protecting it from corrosion.
  • How does a fuel-cell breathalyzer work?
    It oxidizes ethyl alcohol at the anode and reduces oxygen at the cathode; the electrical current produced is proportional to blood alcohol level.
  • What is the key difference between a voltaic cell and an electrolytic cell?
    A voltaic cell produces electrical current from a spontaneous reaction; an electrolytic cell consumes electrical current to drive a nonspontaneous reaction.