Redox Reactions and Oxidation Numbers

Which of the following is a simple definition of oxidation?

Which of the following is an oxidation-reduction reaction?

Which identifies an oxidation-reduction reaction?

Which answer best describes what is happening in the following reaction? 2C8H18 + 25O2 → 16CO2 + 18H2O

What is the oxidation number for S in the compound SO3? (Recall that O has an oxidation number of -2.)

Which best identifies why the rusting of an iron nail in the presence of water and oxygen is an oxidation-reduction reaction?

What is being oxidized in the reaction: CO2(g) + H2(g) → CO(g) + H2O(l)?

Which of the following is an oxidation-reduction reaction?

Given the reaction below, which is the reduced substance? Mg + Cl2 → Mg2+ + 2Cl

In the redox reaction below, which is the reducing agent? MnO2(s) + 4H+(aq) + 2Cl-(aq) → Mn2+(aq) + 2H2O(l) + Cl2(g)

Given the reaction below, which is the oxidized substance? Mg + Cl2 → Mg2+ + 2Cl

Which type of reaction occurs in the following? 2HgO(s) → 2Hg(l) + O2(g)

In a redox reaction, an electron is lost by the reducing agent.

Which describes the oxidizing agent in a chemical reaction?

The presence of which reactant is the best indicator of an oxidation-reduction reaction?

Oxidation-Reduction (Redox) Reactions

Oxidation is defined as the loss of electrons in a chemical reaction.
Redox reactions involve a transfer of electrons between substances, leading to changes in oxidation states.
A reaction showcasing oxidation-reduction is where reactants change oxidation numbers, which indicates that electrons have been transferred.

Examples of Redox Reactions

The reaction Fe2O3 + 3CO → 2Fe + 3CO demonstrates a redox process.
The combustion of octane: 2C8H18 + 25O2 → 16CO2 + 18H2O, presents the oxidation of octane as it reacts with oxygen.
ZnS + 2O2 → ZnSO4 is another example of an oxidation-reduction reaction.

Oxidation Numbers

In the compound SO3, the oxidation number for sulfur (S) is +6, considering oxygen has an oxidation number of -2.
The oxidized substance in the reaction Mg + Cl2 → Mg2+ + 2Cl is magnesium (Mg).
The reduced substance in the reaction Mg + Cl2 → Mg2+ + 2Cl is chlorine (Cl2).

Reducing and Oxidizing Agents

The reducing agent is defined as the substance that donates electrons, resulting in oxidation of itself while reducing another substance. In the redox reaction MnO2 + 4H+ + 2Cl- → Mn2+ + 2H2O + Cl2, Cl- acts as the reducing agent.
The oxidizing agent is the substance that gains electrons. In a reaction, it is characterized by the reduction it facilitates.

Characteristics of Redox Reactions

The rusting of an iron nail in the presence of water and oxygen is a classic example of an oxidation-reduction reaction, wherein electrons are transferred.
In any redox reaction, the reducing agent loses an electron, making the process notable for its electron transfer dynamics.
A decomposition reaction, such as 2HgO → 2Hg + O2, can involve reduction where a metal is reduced during the process.

Indicators of Redox Reactions

The presence of hydrogen gas (H2) in a reaction context is often a strong indicator of an oxidation-reduction reaction occurring.

Explore the concepts of oxidation-reduction reactions and oxidation numbers with this quiz. Learn how electrons are transferred between substances and identify oxidizing and reducing agents in various chemical reactions. Test your understanding of key examples and definitions in redox chemistry.