Consider the generic chemical reaction: $$ \mathrm{A}+2 \mathrm{~B} \longrightarrow \mathrm{C} $$ How many moles of \(C\) are formed upon complete reaction of: (a) \(2 \mathrm{~mol}\) of \(\mathrm{A}\) (b) \(2 \mathrm{~mol}\) of \(\mathrm{B}\) (c) \(3 \mathrm{~mol}\) of \(\mathrm{A}\) (d) \(3 \mathrm{~mol}\) of \(\mathrm{B}\)

A chemical reaction is a process where substances, known as reactants, transform into different substances called products. This transformation follows specific rules and proportions defined by the reaction's stoichiometry. For example, consider the generic reaction:
\[\mathrm{A}+2\mathrm{B} \longrightarrow \mathrm{C}\]
In this case, reactants A and B combine in a definite proportion to produce product C. Understanding a chemical reaction involves identifying the reactants and products, as well as comprehending how they interact during the reaction process. Each substance is involved in the reaction based on a fixed quantitative relationship, which is crucial in predicting the outcomes of the reaction.

The molar ratio is a term that refers to the proportional relationship between the quantities of reactants and products in a chemical reaction, expressed in moles. It is a critical concept in stoichiometry, which allows chemists to calculate how much of each reactant is needed to produce a certain amount of product. In the given equation:
\[\mathrm{A}+2\mathrm{B} \longrightarrow \mathrm{C}\]
The molar ratio tells us that for every mole of A, two moles of B are required to produce one mole of C. This information gives us a powerful tool to predict the amounts of products formed from given quantities of reactants. By writing out molar ratios, such as 1A:2B:1C, we establish a clear roadmap for how many moles of each substance interact in the reaction.

The mole concept is a fundamental principle in chemistry that relates the quantity of matter to the number of particles contained in that matter, whether they are atoms, molecules, ions, or electrons. One mole is defined as exactly 6.02214076×10²³ elementary entities (Avogadro's number). When dealing with chemical reactions, it is crucial to describe the amounts of reactants and products in moles. This allows for the calculation of amounts of substances (in moles) involved in a reaction, such as interpreting chemical formulas and balancing chemical equations. Applying the mole concept to the exercise, we use the stoichiometry of the reaction to determine how many moles of product C will be produced from a given quantity of reactants A and B. It simplifies the comparison and prediction of chemical reactions, enabling students to handle various quantities efficiently and systematically.