Redox and electrochemical reactions concept questions and answers

  1. What is a redox reaction?

    A redox reaction is a type of chemical reaction that involves a transfer of electrons between two species.

  2. What does oxidation and reduction refer to in a redox reaction?

    Oxidation refers to the loss of electrons, while reduction refers to the gain of electrons in a redox reaction.

  3. What is an electrochemical reaction?

    An electrochemical reaction is a type of reaction where oxidation and reduction reactions (redox reactions) produce electrical energy or, conversely, an electrical current drives a chemical reaction.

  4. What are half-reactions in the context of redox reactions?

    Half-reactions are the two parts of a redox reaction, one representing oxidation and the other representing reduction. Each shows the electrons that are either lost in oxidation or gained in reduction.

  5. How is the oxidation number used in redox reactions?

    The oxidation number is a tool used to keep track of electrons in an atom during a redox reaction. An increase in the oxidation number indicates oxidation, while a decrease signifies reduction.

  6. What is a reducing agent and an oxidizing agent?

    A reducing agent is a substance that loses electrons (gets oxidized), thereby causing another substance to be reduced. An oxidizing agent is a substance that gains electrons (gets reduced), thereby causing another substance to be oxidized.

  7. What is the purpose of a salt bridge in an electrochemical cell?

    A salt bridge allows the flow of ions between the anode and cathode compartments of a cell, maintaining charge balance as the redox reaction proceeds.

  8. What’s the difference between a galvanic cell and an electrolytic cell?

    A galvanic cell converts chemical energy into electrical energy (spontaneous redox reaction), while an electrolytic cell uses electrical energy to drive a non-spontaneous redox reaction.

  9. What is the Nernst equation and what does it allow you to calculate?

    The Nernst equation allows you to calculate the potential of a half-cell or full-cell reaction under non-standard conditions. It takes into account the reaction quotient and the temperature.

  10. What is the standard electrode potential?

The standard electrode potential is the potential of a half-cell under standard conditions, with all solutes at 1M concentration and gases at 1 atm pressure.

  1. Why does the anode have a negative sign and the cathode a positive sign in a galvanic cell?

In a galvanic cell, oxidation occurs at the anode and reduction at the cathode. Because electrons are lost at the anode, it is assigned a negative sign. Since electrons are gained at the cathode, it is given a positive sign.

  1. What does it mean when a substance is “reduced”?

When a substance is reduced, it gains electrons. In the process, the oxidation number of the substance decreases.

  1. How does a battery work based on redox reactions?

A battery works by having separate compartments for the oxidation and reduction half-reactions. The flow of electrons from the oxidation half-reaction (anode) to the reduction half-reaction (cathode) generates an electric current that can do work.

  1. What is meant by the term “redox potential”?

Redox potential, also known as oxidation/reduction potential, refers to the tendency of a chemical species to acquire electrons and thereby be reduced.

  1. What happens when a redox reaction reaches equilibrium?

When a redox reaction reaches equilibrium, the forward and reverse reactions proceed at the same rate, and the concentrations of the reactants and products remain constant.

  1. What is the role of a “spectator ion” in a redox reaction?

Spectator ions are ions that exist in the same form on both the reactant and product sides of a chemical reaction. They do not directly participate in the redox reaction.

  1. How are electrochemical reactions used in real-world applications?

Electrochemical reactions have numerous applications, including batteries, fuel cells, corrosion prevention, electroplating, and the industrial production of many chemicals.

  1. What does the Faraday constant represent?

The Faraday constant represents the amount of electric charge carried by one mole of electrons.

  1. What is meant by a “balanced” redox reaction?

A balanced redox reaction means that the number of electrons lost in the oxidation half-reaction equals the number of electrons gained in the reduction half-reaction.

  1. How is spontaneity of a redox reaction determined?

The spontaneity of a redox reaction can be determined by calculating the standard cell potential (E°cell). If E°cell is positive, the reaction is spontaneous. If it is negative, the reaction is non-spontaneous.