Test: Redox Reactions - MCAT MCQ

In redox reactions, oxidation and reduction occur simultaneously. Oxidation refers to the loss of electrons from a species, while reduction refers to the gain of electrons by a species. These reactions involve the transfer of electrons rather than protons. Redox reactions can occur in both aqueous and non-aqueous solutions.

In the given reaction, copper (Cu) is oxidized from its elemental state to Cu²⁺, which involves the loss of electrons. The species that undergoes oxidation is known as the reducing agent, as it causes the reduction (gain of electrons) of another species. Therefore, Cu acts as the reducing agent.

In the given reaction, methane (CH₄) is oxidized to carbon dioxide (CO₂), which involves the loss of electrons. Oxygen (O₂) is reduced to form water (H₂O), which involves the gain of electrons. Therefore, CH₄ is oxidized, and O₂ is reduced.

Redox reactions involve the transfer of electrons between reactants, resulting in a change in oxidation numbers. They typically involve the presence of an oxidizing agent (electron acceptor) and a reducing agent (electron donor). The formation of new covalent bonds may or may not occur in a redox reaction, depending on the specific reaction and the nature of the reactants.

In most compounds, oxygen has an oxidation number of -2. However, there are exceptions, such as in peroxides (e.g., H₂O₂), where oxygen has an oxidation number of -1. The oxidation number of hydrogen is +1 in most compounds, except in metal hydrides, where it is -1. The sum of oxidation numbers in a neutral compound is always zero.

Disproportionation reactions involve a species being simultaneously oxidized and reduced. In the given reaction, hydrogen peroxide (H₂O₂) is both oxidized to water (H₂O) and reduced to oxygen gas (O₂). This reaction illustrates disproportionation.

The combustion of gasoline in an engine is a common example of a redox reaction. In this process, gasoline (a hydrocarbon fuel) reacts with oxygen in the presence of a spark or heat, leading to the formation of carbon dioxide and water. This reaction involves the oxidation of carbon in gasoline and the reduction of oxygen.

In a redox reaction, if one species undergoes reduction (i.e., gains electrons), another species must undergo oxidation (i.e., lose electrons). These processes occur simultaneously to maintain charge balance within the reaction.

Oxidation refers to an increase in the oxidation number of an atom, indicating the loss of electrons. Reduction, on the other hand, involves a decrease in the oxidation number of an atom, indicating the gain of electrons. While oxidation often involves the loss of electrons and reduction involves the gain of electrons, these terms specifically describe changes in oxidation numbers.

Cellular respiration involves the breakdown of glucose (C6H12O6) in the presence of oxygen to produce carbon dioxide, water, and energy in the form of ATP. This process is an example of a redox reaction, as glucose is oxidized to carbon dioxide, and oxygen is reduced to water.