What will be the product obtained by heating \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} ?\) (a) \(\mathrm{Cr}_{2} \mathrm{O}_{3}+\mathrm{N}_{2}+\mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{N}_{2} \mathrm{O}+\mathrm{H}_{2}+\mathrm{Cr}_{2} \mathrm{O}_{3}\) (c) \(\mathrm{Cr}_{2} \mathrm{O}_{3}+\mathrm{NH}_{3}+\mathrm{H}_{2} \mathrm{O}+\mathrm{N}_{2}\) (d) \(\mathrm{NH}_{3}+\mathrm{Cr}_{2} \mathrm{O}_{3}\)

Understanding the decomposition of ammonium dichromate is crucial for students studying chemistry. When heated, ammonium dichromate \(\left(\mathrm{NH}_{4}\right)_{2}\mathrm{Cr}_{2} \mathrm{O}_{7}\) decomposes in a reaction that's both visually striking and chemically interesting. It undergoes a chemical change where the original compound breaks down into simpler substances.

This reaction is a classic demonstration of a decomposition reaction, an essential type of chemical reaction where a single reactant yields multiple products. In this particular reaction, the application of heat serves as a form of energy input, prompting the ammonium dichromate to break down. The resulting products are chromium(III) oxide \(\mathrm{Cr}_{2} \mathrm{O}_{3}\), nitrogen gas \(\mathrm{N}_{2}\), and water vapor \(\mathrm{H}_{2} \mathrm{O}\). It is noteworthy to mention that this reaction is also exothermic, releasing energy in the form of heat and light, which often manifests as a 'volcano' effect when carried out in a lab setting.

This reaction underlines the importance of understanding the behavior of chemicals under different conditions and the mechanisms by which they transform into new substances.

The chemical formula of a substance is a symbolic representation of its constituent elements and the proportion of atoms of each element present in the compound. For instance, in ammonium dichromate \(\left(\mathrm{NH}_{4}\right)_{2}\mathrm{Cr}_{2} \mathrm{O}_{7}\), the formula indicates that the compound contains two ammonium ions \(\mathrm{NH}_{4}^{+}\) and one dichromate ion \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\).

Understanding chemical formulas is fundamental for students as they provide essential information about the substance. They outline how many atoms of each element are required to form a molecule of the compound, which can further be used to understand the stoichiometry of a reaction. In educational settings, helping students visualize molecules through models or drawings can significantly improve their grasp of the concepts tied to chemical formulas.

A balanced chemical equation is vital in communicating the precise quantities of reactants and products involved in a chemical reaction. It follows the law of conservation of mass, which states that matter cannot be created or destroyed, only transformed. In the equation for the decomposition of ammonium dichromate, we write:

\[\left(\mathrm{NH}_{4}\right)_{2}\mathrm{Cr}_{2} \mathrm{O}_{7} \xrightarrow{\Delta} \mathrm{Cr}_{2} \mathrm{O}_{3} + \mathrm{N}_{2} + 4\mathrm{H}_{2} \mathrm{O}\]

This equation is balanced because it has an equal number of each type of atom on both sides, satisfying the law of conservation of mass. To help students learn to balance equations, focusing on systematic approaches and reinforcing the concept of the conservation law can be beneficial. Some strategies include starting by balancing elements that appear in only one reactant and one product, and saving hydrogen and oxygen for last, which often appear in multiple compounds in a reaction.