Write a balanced equation describing each of the following chemical reactions. (a) Solid potassium chlorate, \(\mathrm{KClO}_{3}\), decomposes to form solid potassium chloride and diatomic oxygen gas. (b) Solid aluminum metal reacts with solid diatomic iodine to form solid \(\mathrm{Al}_{2} \mathrm{I}_{6}\) (c) When solid sodium chloride is added to aqueous sulfuric acid, hydrogen chloride gas and aqueous sodium sulfate are produced. (d) Aqueous solutions of phosphoric acid and potassium hydroxide react to produce aqueous potassium dihydrogen phosphate and liquid water.

Stoichiometry is the cornerstone of chemical equations, as it allows us to quantify the relationships between reactants and products in a chemical reaction. It involves calculations that rely on the mole concept and the law of conservation of mass to ensure that atoms are neither created nor destroyed in reactions.

Thinking of stoichiometry as a recipe is helpful; just as a recipe specifies the exact amount of each ingredient needed, stoichiometry provides the precise measure of reactants required to produce a set amount of product. In the exercise, this is seen when balancing oxygen atoms by using coefficients that maintain the ratio of elements according to their mole ratios.

By using stoichiometry, one can predict the amount of products formed from given reactants or determine the amount of reactants needed to create a certain amount of products. This is not only essential in academic problems but also vital in real-world applications such as pharmaceuticals, materials science, and environmental engineering where precise chemical formulations are crucial.

Chemical reactions are processes where reactants transform into products through the breaking and forming of chemical bonds. There are many types of chemical reactions, including synthesis, decomposition, single replacement, and double replacement reactions.

In our exercise, for example, we have a decomposition reaction where potassium chlorate breaks down into potassium chloride and oxygen gas. It is essential to identify the type of reaction to balance the equation correctly, as each type follows different patterns.

Chemical reactions are depicted through chemical equations that need to be balanced to reflect the conservation of mass. When balancing equations, it’s important to adjust the coefficients, the numbers before the chemical formulas, to ensure that the same number of each type of atom appears on both sides of the equation. This reflects the physical reality that in a closed system, atoms are not lost or gained—only rearranged.

The mole concept is a fundamental idea in chemistry that relates the mass of substances to the number of particles or entities they contain. One mole corresponds to Avogadro's number, which is approximately \(6.022 \times 10^{23}\) entities, whether they are atoms, molecules, ions, or electrons.

This concept allows chemists to