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Chapters 13 & 14 : (Electrochemical Cells (Cells and Batteries…

- - - - Image https://chem.libretexts.org/@api/deki/files/159/voltaic_cell_diagram.png?revision=1
      - A cell is made of 2 electrodes, or solid metal conductors
        
        Cathode is positive electrode
        
        Anode is negative electrode
      - Made of electrolyte, or aqueous conductor
      - Electrons flow from anode to cathode [A/C power!]
      - Cations travel to cathode, anions travel to anode
    - - Primary Cells are single-use and meant to be disposed of after reaction is over
      - Secondary cells are rechargeable, reaction can be reversed using electric impulse
      - Fuel cells have very high energy density, and have a continuous supply of fuel to keep the cell operating
    - - Voltaic cells also include porous boundaries, eg. salt bridges and porous cups
        
        Voltaic cells are comprised of 2 half-cells, where 2 half-reactions separated by a porous boundary occur
      - Inert electrodes can be used when a electrolyte solution's electrode is not compatible with the cell, and an electrode thant does not interfere with the reaction is needed
    - - Half-reactions contain all entities in cell
      - SATP condition
      - 1.0 mol/L concentration for electrolyte solutions
    - - Electrolysis: A power supply is used to force a spontaneous reaction
        
        used to recharge secondary cells
      - Electroplating (putting a layer of metal on top of other metal) and electrorefining (obtaining pure metal at cathode) are two methods of using an electrolytic cell
      - The reaction in an electrolytic cell in non-spontaneous, and has a negative standard cell potential
      - Cathode is negative, Anode is positive
      - Chloride Anomaly: sometimes we don't get predicted results and unexpected products are produced
  - - - Impressed current: forcing a current through a metal to protect it
      - Sacrificial anode: attaching a stronger reducing agent to protect the expensive metal
    - - Galvanization (Zinc coating)
      - Using metal or other substance to coat an easily corroded metal
    - - Iron rusts with water and oxygen
  - - - Faraday's Constant:
        9.65 x 10^4 Coulombs/mol of electrons transferred
      - Relationship between mass produced or consumed at n electrode is directly proportional to the time the cell operates
      - Moles of electrons = (Current x time) / Faraday's constant Rearrange to find other values.
    - - Q = It
      - Coulombs(C)- unit of charge Amperes (I)- Coulomb per second Charge (Q)- amount of coulombs Time (t)- in seconds
      - Half-cells have different calculations even though the same amount of current (electrons) pass through each
      - Steps: http://www.sparknotes.com/chemistry/stoichiometry/stoichiometriccalculations/section2/
- - - - Single replacement reactions are comprised of half-reactions that gain or lose electrons
        
        Oxidation half-reaction: Fe(s)→Fe3+(aq)+3e−
        Reduction half-reaction: Cu+(aq)+e−→Cu(s)
        Net reaction: Cu+(aq)+Fe(s)→Fe3+(aq)+Cu(s)
        
        Half-reactions contain gained or lost electrons that cancel out in the net reaction.
      - Oxidation occurs when entities lose electrons. Reduction occurs when entities gain electrons. [OIL RIG - Oxidation is loss, reduction is gain]
      - To write and balance half reactions: https://chem.libretexts.org/Core/Analytical_Chemistry/Electrochemistry/Redox_Chemistry/Balancing_Redox_reactions
        1) List all entities (including h2o)
        2) identify strongest oxidizing agent and strongest reducing agent
        3)copy reduction half-reaction
        4) flip oxidation half-reaction then copy 5)find Lowest common multiple of electrons lost and gained
        6) cancel out repeating entities and write net equation, predict spontaneity
    - - Rules for assigning ONs
        
        Molecules and atoms are 0
        
        Ions equal their charge
        
        Hydrogen is usually +1
        
        Oxygen is usually -2
        
        An entity's charge is the sum of it's ONs.
        
        The most electronegative atom is negative,
        and the other atom is positive.
      - Oxidation Numbers match oxidation state for an atom. This is the apparent charge an atom would have if the valence electron in an entity were attracted to the most electronegative atom.
      - The ON of a particular entity can change depending on the compound.
  - - - Strength Table: https://chem.libretexts.org/@api/deki/files/111867/Standardpotentials.png?revision=1&size=bestfit&width=445&height=493
    - - If the oxidation half-cell has a higher cell potential than the reduction half-reaction, the reaction is spontaneous as well.