Question

What does it mean for a substance to be oxidized? The term "oxidation" originally came from substances reacting with oxygen gas. Explain why a substance that reacts with oxygen gas will always be oxidized.

Short answer

A substance that reacts with oxygen gas will always be oxidized because during this reaction, it gains an oxygen molecule and loses electrons to oxygen. The addition of the oxygen molecule increases its oxidation state, which means it undergoes oxidation. In these reactions, the substance is usually the one donating electrons, further confirming that it is being oxidized.

Step-by-step solution

Define oxidation

Oxidation is a chemical process in which an atom, ion, or molecule loses one or more electrons, resulting in an increase in its oxidation state. Oxidation often involves the addition of oxygen to a molecule or the removal of hydrogen from it.

Discuss the process of a reaction with oxygen gas

When a substance reacts with oxygen gas, it is generally undergoing a chemical reaction known as a combustion reaction. In these reactions, oxygen molecules are added to the reacting substance, forming new compounds as a result. Additionally, these reactions often involve the transfer of electrons between the reacting substance and oxygen.

Connect the concepts

A substance that reacts with oxygen gas will always be oxidized because, during the reaction, the substance gains an oxygen molecule and loses electrons to oxygen. The addition of the oxygen molecule to the reacting substance increases its oxidation state, satisfying the definition of oxidation. Furthermore, in such reactions, the reacting substance is usually the one that donates the electrons, making it the one undergoing oxidation. Therefore, a substance that reacts with oxygen gas will always be oxidized.

Key concepts

Chemical Reactions

Chemical reactions are processes where substances, called reactants, transform into new substances, known as products. During a chemical reaction, the atoms in the reactants rearrange, leading to the formation of new chemical bonds.

• Reactants: Initial substances that undergo change.
• Products: New substances formed as a result of the chemical reaction.
• Chemical bonds: Forces that hold atoms together within molecules.

Chemical reactions can vary in type, involving different processes such as synthesis, decomposition, and combustion. Understanding chemical reactions is essential as they form the foundation of chemistry, explaining how substances change their structure and properties in the presence of various conditions.

Electrons

Electrons are tiny subatomic particles with a negative charge. They are found in orbitals surrounding the nucleus of an atom and play a crucial role in chemical reactions. Electrons are key to forming chemical bonds, as they can be shared or transferred between atoms to create stable substances.

• Negative charge: Electrons have a charge of -1, balancing the positive charge of protons.
• Orbitals: Regions around the nucleus where electrons are likely to be found.
• Chemical bonds: Result from the exchange or sharing of electrons between atoms.

Understanding electron behavior is fundamental for predicting how substances will react with one another, as it is the electrons that engage in interactions that lead to chemical changes.

Oxidation State

Oxidation state, sometimes referred to as oxidation number, is a concept that helps in understanding the degree of oxidation in an atom within a compound. It signifies the hypothetical charge that an atom would have if all bonds involving it were purely ionic.

• Oxidation increase: Corresponds to the loss of electrons.
• Reduction: Involves gain of electrons, decreasing the oxidation state.
• Oxidation and reduction together are called redox reactions.

Tracking the changes in oxidation state of atoms during a reaction can provide insights into which substances are oxidized or reduced. This helps in recognizing patterns in chemical reactions and predicting reaction pathways.

Combustion Reaction

Combustion reactions are a type of chemical reaction where a substance rapidly reacts with oxygen to release energy, usually in the form of heat and light. These reactions often involve hydrocarbons reacting with oxygen to form carbon dioxide and water.

• Exothermic: Releases energy, making them feel hot.
• Products: Typically carbon dioxide and water.
• Commonly involve organic compounds like fuels.

In combustion reactions, the substance that reacts with oxygen undergoes oxidation. This happens as the substance loses electrons to oxygen, thus increasing its oxidation state. Such reactions are crucial in everyday applications like powering engines and heating homes, highlighting their significance in both industrial and residential settings.