Ammonia reacts with oxygen to yield nitrogen and water. \(4 \mathrm{NH}_{3}(g)+3 \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{N}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(l)\) Given this chemical equation, as well as the number of moles of the reactant or product indicated below, determine the number of moles of all remaining reactants and products. \(\begin{array}{ll}{\text { a. } 3.0 \mathrm{mol} \mathrm{O}_{2}} & {\text { c. } 1.0 \mathrm{mol} \mathrm{N}_{2}} \\ {\text { b. } 8.0 \mathrm{mol} \mathrm{NH}_{3}} & {\text { d. } 0.40 \mathrm{mol} \mathrm{H}_{2} \mathrm{O}}\end{array}\)

To start with stoichiometry in chemical reactions, the balanced chemical equation is essential. It ensures that the number of atoms for each element is the same on both sides of the equation. This is according to the Law of Conservation of Mass. In our example, we have the reaction of ammonia (NH₃) with oxygen (O₂) to produce nitrogen (N₂) and water (H₂O). The balanced equation is:

4 NH₃(g) + 3 O₂(g) → 2 N₂(g) + 6 H₂O(l)

Balancing the equation helps us understand how reactants turn into products at an atomic level. We can see that 4 molecules of NH₃ react with 3 molecules of O₂ to form 2 molecules of N₂ and 6 molecules of H₂O. This sets the stage for further calculations and understanding of the reaction.

Mole calculations allow us to quantify the amounts of reactants and products in a chemical reaction. The mole is a standard unit in chemistry that represents a large number of entities (Avogadro's number, 6.022 × 10²³).

In our example, we make several mole calculations to determine the amount of each substance involved in the reaction. For instance:

• Given 3.0 moles of O₂, we can calculate the moles of NH₃ required, N₂ produced, and H₂O produced.
• Given 8.0 moles of NH₃, we can similarly calculate the moles of O₂ needed, and the moles of products produced.

By understanding the mole relationships from the balanced equation, we can solve for any reactant or product in the reaction.

The reactant-product relationship is crucial in stoichiometry. It is defined by the coefficients in the balanced chemical equation. These coefficients tell us the proportions in which substances react and are formed. In our reaction between ammonia and oxygen:

• 4 moles of NH₃ react with 3 moles of O₂.
• This reaction yields 2 moles of N₂ and 6 moles of H₂O.

When given a certain amount of one reactant, these relationships help us calculate the amounts of all other reactants and products. For example, knowing 3.0 moles of O₂ are used, we follow the ratio 3:4 to find needing 4.0 moles of NH₃. Likewise, the ratio 3:6 gives us 6.0 moles of H₂O produced. These ratios are direct conversions that help quantify chemical reactions.

Chemical stoichiometry uses balanced chemical equations to calculate the quantities of reactants and products. It involves steps like balancing the equation, determining mole ratios, and performing mole-to-mole conversions.

In our example, ammonia reacts with oxygen and the stoichiometry involves these steps: 1. **Balancing the Equation**: Ensures elements are equal on both sides. 2. **Mole Ratios**: Retrieved from the balanced equation (e.g., 4 NH₃: 3 O₂). 3. **Calculations**: Converting given quantities into moles using the ratios.
For example, given 8.0 moles of NH₃, we find the moles of O₂ needed by multiplying 8.0 by (3 moles O₂ / 4 moles NH₃). This results in 6.0 moles O₂. Similarly, we calculate the moles of N₂ and H₂O produced.

Stoichiometry demystifies the proportions and conversions required for chemical reactions, making it an essential tool in chemistry.