Electrode potentials and cells

• What type of reactions do electrochemical cells use?

  Redox reactions

  
• What creates a flow of electrons in electrochemical cells?

  Electron transfer between products
• What is produced between the two electrodes in an electrochemical cell?

  A potential difference
• What do most electrochemical cells consist of?

  Two solutions with metal electrodes
• What is the function of a salt bridge in an electrochemical cell?

  To carry the flow of charge
• What is each solution in an electrochemical cell called?

  Half-cell
• What does the cell potential indicate in a half-cell?

  How it will react in a redox reaction

  
• What are the rules for conventional cell representation?

  • Most negative potential on the left
  • Most oxidised species next to the salt bridge
  • Salt bridge shown with a double line
  • Include state symbols
• What is the cell potential of the standard hydrogen electrode (SHE)?

  0.00V
• Under what conditions is the standard hydrogen electrode measured?

  Standard conditions
• What are the standard conditions for measuring SHE?

  1.0 moldm^-3, 298K, 100 kPa
• Why are platinum electrodes used in the standard hydrogen electrode?

  They are inert and conduct electricity
• What does a negative cell potential indicate?

  Substances are more easily oxidised
• What does a positive cell potential indicate?

  Substances are more easily reduced
• How is overall cell EMF calculated?

  Right potential minus left potential

  
• What does a positive overall cell potential indicate about the reaction?

  The reaction is spontaneous and favourable
• What is the anticlockwise rule for combining half-cell reactions?

  1. Write most negative EMF on top
  2. Draw anticlockwise arrows around reactions
  3. Balance electrons on both sides
  4. Write out the cell reaction
• What makes a species a better oxidising agent?

  Very positive electrode potentials
• What makes a species a better reducing agent?

  Very negative electrode potentials
• How does increasing concentration affect cell EMF?

  Makes cell EMF more positive
• How does increasing pressure affect cell EMF?

  Makes cell EMF more negative
• What types of electrochemical cells are there for commercial use?

  Non-rechargeable, rechargeable, fuel cells
• What characterizes a rechargeable cell?

  It undergoes a reversible reaction
• What is commonly used as a rechargeable battery?

  Lithium ion cells
• What electrodes are used in lithium ion cells?

  Lithium Cobalt Oxide and Graphite

  
• What is required to recharge a cell?

  A current has to be applied
• What is a characteristic of non-rechargeable cells?

  Reactions are impossible to reverse
• What is the most common type of fuel cell?

  Hydrogen fuel cell
• What do hydrogen fuel cells use to generate current?

  A continuous supply of Hydrogen and Oxygen
• What is the waste product of hydrogen fuel cells?

  Water
• What are the downsides of hydrogen fuel cells?

  High flammability and expensive production
• What are the advantages and disadvantages of hydrogen fuel cells?

  Advantages:

  • Generates current without recharging
  • Produces only water as waste

  
  

  Disadvantages:

  • High flammability of hydrogen
  • Expensive to produce