Write a balanced chemical equation for the reaction of an excess of oxygen with each of the following. Remember that oxygen is a strong oxidizing agent and tends to oxidize an element to its maximum oxidation state. (a) Mg (b) Rb (c) Ga (d) \(\mathrm{C}_{2} \mathrm{H}_{2}\) (e) CO

Understanding oxidation states is essential in balancing chemical equations. An oxidation state, often called an oxidation number, signifies the degree of oxidation (loss of electrons) of an atom in a chemical compound. Oxidation states can be positive, negative, or zero, and they are used to determine how electrons are distributed in molecules.

In the exercise, we see examples such as magnesium (Mg) adopting an oxidation state of +2 when it reacts with oxygen (O2) to form magnesium oxide (MgO). Similarly, rubidium (Rb) takes on a +1 oxidation state in rubidium oxide (Rb2O), and gallium (Ga) has a +3 oxidation state in gallium oxide (Ga2O3).

When an element reacts with oxygen, it often reaches its maximum oxidation state due to oxygen's strong oxidizing ability. For instance, carbon in carbon monoxide (CO) is at a +2 oxidation state but is oxidized to a +4 state in carbon dioxide (CO2).

A chemical reaction involves the transformation of one or more substances into new substances. The reaction between oxygen and other elements, as shown in the exercise, is a classic example of a combination reaction, where elements combine to form compounds.

During a chemical reaction, atoms are not destroyed or created; they are merely rearranged. In the case of our exercise problem, elemental magnesium combines with oxygen to form magnesium oxide, and elemental rubidium reacts similarly with oxygen to form rubidium oxide. These transformations represent fundamental principles in chemistry—the conservation of mass and the reorganization of atoms during chemical processes.

To represent these reactions accurately, we use chemical equations, which show the reactants on the left side and the products on the right side. These equations provide a symbolic representation of what occurs at the molecular level during a chemical reaction.

Balancing chemical equations is like solving a puzzle where you ensure that the number of atoms of each element is the same on both sides of the equation to satisfy the law of conservation of mass. This exercise demonstrates the step-by-step approach to achieving a balanced equation, a critical skill in understanding chemical reactions.

To balance an equation, we adjust the coefficients—the numbers placed before the chemical formulas—without changing the actual formulas of the compounds. For example, in the oxidation of magnesium (Mg), we use a coefficient of 2 for Mg on the left-hand side to balance the two oxygen atoms in the O2 molecule on the right-hand side, forming two units of MgO. Balancing equations ensures that atoms are neither lost nor gained during the reaction, aligning with the principle that matter is neither created nor destroyed.

The complexity of balancing equations increases with more complex molecules, such as acetylene (C2H2), which requires balancing multiple types of atoms. Yet, the underlying approach remains the same: identify the number of atoms of each element on both sides and adjust coefficients until they match.