Redox Reactions - SS1 Chemistry Past Questions and Answers - page 1
Oxidation is the process that involves:
Gain of electrons
Loss of electrons
Formation of covalent bonds
Increase in temperature
Reduction is the process that involves:
Gain of electrons
Loss of electrons
Formation of ionic bonds
Decrease in temperature
In a redox reaction, the species that undergoes oxidation is called:
Oxidising agent
Reducing agent
Catalyst
None of the above
In a redox reaction, the species that undergoes reduction is called:
Oxidising agent
Reducing agent
Catalyst
None of the above
The oxidising agent is responsible for:
Gaining electrons
Losing electrons
Providing a medium for the reaction
Both gaining and losing electrons
Which of the following statements is true about oxidation and reduction?
Oxidation and reduction always occur together.
Oxidation and reduction can occur independently.
Oxidation always involves a gain of electrons.
Reduction always involves a loss of electrons.
Which of the following is an example of oxidation?
Conversion of water into hydrogen and oxygen gas
Rusting of iron
Formation of table salt from sodium and chlorine
Photosynthesis in plants
Which of the following is an example of reduction?
Conversion of water into hydrogen and oxygen gas
Rusting of iron
Formation of table salt from sodium and chlorine
Photosynthesis in plants
In a redox reaction, the electrons are transferred from the:
Oxidising agent to the reducing agent
Reducing agent to the oxidising agent
Catalyst to the reactants
None of the above
Define oxidation and reduction and explain their significance in chemical reactions. Provide examples to illustrate these processes.
Oxidation and reduction are fundamental processes in chemistry that involve the transfer of electrons between chemical species.
Oxidation:
Oxidation refers to the loss of electrons or an increase in oxidation state of an atom, ion, or molecule. It involves the addition of oxygen or the removal of hydrogen from a substance. Oxidation is often associated with the loss of energy or the formation of more stable compounds.
Example: The oxidation of iron (Fe) to form iron(III) oxide (Fe2O3) involves the loss of electrons by iron atoms, resulting in the rusting of iron.
Reduction:
Reduction refers to the gain of electrons or a decrease in oxidation state of an atom, ion, or molecule. It involves the addition of hydrogen or the removal of oxygen from a substance. Reduction is often associated with the gain of energy or the formation of less stable compounds.
Example: The reduction of silver ions (Ag+) to form silver metal (Ag) involves the gain of electrons by silver ions, leading to the deposition of silver onto a surface during silver plating.
Significance of Oxidation and Reduction:
Oxidation and reduction play a crucial role in chemical reactions and various natural and industrial processes:
- Redox Reactions: Oxidation and reduction always occur together in a process called a redox (reduction-oxidation) reaction. These reactions involve the transfer of electrons from the reducing agent (substance undergoing oxidation) to the oxidising agent (substance undergoing reduction).
- Energy Production: Oxidation-reduction reactions are central to energy production in living organisms. For example, cellular respiration involves the oxidation of glucose (C6H12O6) to produce energy in the form of adenosine triphosphate (ATP).
- Corrosion and Rusting: Oxidation of metals leads to the formation of metal oxides, resulting in corrosion and rusting. Understanding oxidation processes is important in preventing or controlling the deterioration of materials.
- Fuel Cells and Batteries: Electrochemical cells, such as fuel cells and batteries, rely on redox reactions to generate electricity. The oxidation of a fuel (e.g., hydrogen) and the reduction of an oxidising agent (e.g., oxygen) produce electrical energy.