Redox and electrochemical reactions problems and solutions

  1. What is a redox reaction? Solution: A redox (reduction-oxidation) reaction is a type of chemical reaction that involves a transfer of electrons between two species.

  2. What is an oxidation state and how is it used in redox reactions? Solution: An oxidation state is a number that represents the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. It is used in redox reactions to determine which species is oxidized and which is reduced.
  3. What happens to the species that is oxidized in a redox reaction? Solution: The species that is oxidized in a redox reaction loses electrons.
  4. What happens to the species that is reduced in a redox reaction? Solution: The species that is reduced in a redox reaction gains electrons.
  5. How do you balance a redox reaction in acidic solution? Solution: To balance a redox reaction in an acidic solution, one can use the half-reaction method which involves balancing the atoms and charges in each half-reaction separately, and then combining the half-reactions to give the balanced overall equation.
  6. How do you balance a redox reaction in basic solution? Solution: Balancing a redox reaction in a basic solution is similar to the process in an acidic solution. After using the half-reaction method, additional OH⁻ ions are added to both sides of the equation to neutralize H⁺ ions in the equation and form water.
  7. What is an electrochemical cell? Solution: An electrochemical cell is a device that generates an electric current from a redox reaction or uses an electric current to cause a redox reaction.
  8. What is the difference between a galvanic cell and an electrolytic cell? Solution: A galvanic cell generates an electric current from a spontaneous redox reaction, while an electrolytic cell uses an electric current to drive a non-spontaneous redox reaction.
  9. How do you determine the cell potential of a galvanic cell? Solution: The cell potential of a galvanic cell is determined by subtracting the standard electrode potential of the half-reaction that occurs at the anode (the oxidation half-reaction) from the standard electrode potential of the half-reaction at the cathode (the reduction half-reaction).
  10. What is the role of the salt bridge in a galvanic cell? Solution: The salt bridge completes the electrical circuit and allows the flow of ions, which balances the charge in the cell compartments and allows the redox reaction to proceed.
  11. What does a positive cell potential mean in terms of the spontaneity of the reaction? Solution: A positive cell potential means that the reaction is spontaneous.
  12. What does a negative cell potential mean in terms of the spontaneity of the reaction? Solution: A negative cell potential means that the reaction is non-spontaneous.
  13. What is the Nernst equation and how is it used in electrochemistry? Solution: The Nernst equation relates the cell potential at non-standard conditions to the standard cell potential, temperature, and reaction quotient. It allows for the calculation of cell potentials under various conditions.
  14. How is Faraday’s law of electrolysis used in electrochemistry? Solution: Faraday’s law of electrolysis relates the amount of substance produced or consumed at an electrode during electrolysis to the amount of electricity that is applied. It can be used to determine quantities such as the amount of product formed or the amount of electric current required in electrolysis.
  15. How can an electrochemical cell be used to do work? Solution: An electrochemical cell can do work by converting the energy released from a redox reaction into electrical energy, which can be used to power electrical devices.
  16. How is redox chemistry used in batteries? Solution: Batteries use redox chemistry to convert chemical energy into electrical energy. They contain two different substances that undergo redox reactions, allowing for the transfer of electrons and the generation of an electric current.
  17. What is a fuel cell and how does it relate to redox reactions? Solution: A fuel cell is a type of electrochemical cell that converts the chemical energy from a fuel into electricity through a pair of redox reactions.
  18. How does the concentration of reactants affect the cell potential? Solution: According to the Nernst equation, the cell potential is directly related to the logarithm of the concentrations of the reactants and products. If the concentration of the reactants decreases, the cell potential will decrease, and vice versa.
  19. How does the temperature affect the cell potential? Solution: According to the Nernst equation, the cell potential is directly proportional to the temperature. An increase in temperature will increase the cell potential if the reaction is endothermic, and decrease it if the reaction is exothermic.
  20. How can you determine the standard cell potential from a table of standard reduction potentials? Solution: The standard cell potential can be determined by subtracting the standard reduction potential for the oxidation half-reaction from the standard reduction potential for the reduction half-reaction.

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