Washington Esthetician State Board Practice Exam

What happens during an oxidation-reduction reaction?

1. Energy is always retained

2. One substance is oxidized while another is reduced

3. Both substances must be gases

4. Only solid substances participate

The correct answer is: One substance is oxidized while another is reduced

In an oxidation-reduction reaction, often referred to as a redox reaction, one substance undergoes oxidation while another undergoes reduction. Oxidation is defined as the loss of electrons, leading to an increase in oxidation state, while reduction is the gain of electrons, which decreases oxidation state. This process is fundamental in various chemical and biological systems, as it is involved in energy transfer, metabolism, and even certain types of reactions in esthetics, such as those involving chemical agents applied to the skin. The nature of these reactions means it's not about the physical state of the substances involved (gas, liquid, or solid) but rather the transfer of electrons from one substance to another. This is why the choices that suggest both substances must be gases or that only solid substances participate are not accurate. Additionally, the concept of energy retention does not specifically characterize redox reactions since energy can be released or absorbed during these reactions, so it isn't a definitive aspect of what occurs in an oxidation-reduction process.