Aluminum hydroxide reacts with sulfuric acid as follows: $$ 2 \mathrm{Al}(\mathrm{OH})_{3}(s)+3 \mathrm{H}_{2} \mathrm{SO}_{4}(a q) \longrightarrow \mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}(a q)+6 \mathrm{H}_{2} \mathrm{O}(l) $$ Which is the limiting reactant when 0.500 mol \(\mathrm{Al}(\mathrm{OH})_{3}\) and 0.500 \(\mathrm{mol} \mathrm{H}_{2} \mathrm{SO}_{4}\) are allowed to react? How many moles of \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\) can form under these conditions? How many moles of the excess reactant remain after the completion of the reaction?

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It allows chemists to predict the amounts of substances consumed and produced in a given reaction. Crucial to understanding stoichiometry is the concept of the mole, which is a unit for counting particles of matter, typically atoms, molecules, or ions.

When performing stoichiometric calculations, a balanced chemical equation is vital because it shows the proportional relationship between reactants and products, based on the law of conservation of mass. This fundamental principle states that in a chemical reaction, mass is neither created nor destroyed, so the mass of the reactants must equal the mass of the products. In practice, this means that if we know the quantity of one substance in a reaction, we can calculate the quantities of all the other substances.

• Identify the 'mole ratio' from the balanced equation.
• Use the mole ratio to convert between moles of reactant and moles of product.
• Apply the 'limiting reactant' concept to determine which reactant will be completely used up first, thus stopping the reaction and determining the maximum amount of product that can be formed.

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Reactants are substances initially present in a chemical reaction that are consumed during the reaction to make products. When writing a chemical equation, reactants are listed on the left-hand side, while products are listed on the right-hand side.

• A chemical reaction can involve elements, compounds, or both.
• Chemical equations must be balanced, meaning the number of atoms for each element in the reactants must equal the number of atoms in the products.

The reaction between aluminum hydroxide and sulfuric acid is an example of a double displacement reaction. This involves two compounds swapping parts to form two new compounds. Understanding the type of reaction helps predict the products and write a balanced chemical equation, which is the starting point for any stoichiometric calculation.

The mole ratio, derived from the coefficients of a balanced chemical equation, is a critical aspect of stoichiometry. It indicates the proportions of reactants and products that interact in a reaction. For example, in our chemical equation, the mole ratio between \(\mathrm{Al(OH)}_{3}\) and \(\mathrm{H}_{2} \mathrm{SO}_{4}\) is 2:3, which means two moles of aluminum hydroxide react with three moles of sulfuric acid to produce products.

When solving stoichiometry problems, you use these ratios to convert between moles of one substance to moles of another. The mole ratio is essentially a conversion factor that bridges the gap between reactants and products. This provides a clear pathway to answer questions about the quantities of substances before and after a chemical reaction.