Question

Write a balanced equation for the reaction of an excess of \(\mathrm{O}_{2}\) with each of the following elements: (a) Li (b) \(\mathrm{P}\) (c) \(\mathrm{Al}\) (d) Si

Short answer

(a) 4Li + O₂ → 2Li₂O; (b) 4P + 5O₂ → 2P₂O₅; (c) 4Al + 3O₂ → 2Al₂O₃; (d) Si + O₂ → SiO₂.

Step-by-step solution

Understanding Oxidation

When an element reacts with oxygen, it forms an oxide. For example, lithium (Li) will react with oxygen to form lithium oxide, phosphorus (P) with oxygen to form phosphorus pentoxide, aluminum (Al) with oxygen to form aluminum oxide, and silicon (Si) with oxygen to form silicon dioxide.

Writing the Formulas of Oxides

Identify the oxide formed for each element. Lithium forms Li₂O, phosphorus forms P₂O₅, aluminum forms Al₂O₃, and silicon forms SiO₂.

Balancing the Chemical Equations

Balance each reaction by ensuring the number of atoms of each element on the reactant side equals the number of atoms on the product side. - **Li with O₂**: 4Li + O₂ → 2Li₂O - **P with O₂**: 4P + 5O₂ → 2P₂O₅ - **Al with O₂**: 4Al + 3O₂ → 2Al₂O₃ - **Si with O₂**: Si + O₂ → SiO₂

Verification

Check each equation to confirm it is balanced. Count the atoms of each element on both sides and ensure they are equal.

Key concepts

Understanding Oxidation

Oxidation is a key concept in chemistry that involves the loss of electrons by a molecule, atom, or ion. In the context of reacting with oxygen, oxidation refers to the addition of oxygen to a substance. This process results in the formation of oxides, where oxygen combines with other elements to form compounds. For example, when lithium is oxidized by oxygen, it forms lithium oxide. Oxidation is part of the broader category of redox reactions (reduction-oxidation reactions), where Oxidation involves electron loss and reduction involves electron gain. By focusing on oxidation, we can understand why and how different elements form oxides when exposed to an excess of oxygen.

The Basics of Chemical Reactions

Chemical reactions involve the transformation of reactants into products through the breaking and forming of bonds. During a reaction, the atoms of the substances involved rearrange to create new compounds. In the given exercise, elements like Li, P, Al, and Si react with oxygen to form respective oxides. There are several types of chemical reactions, and the ones mentioned before are synthesis reactions, where two or more reactants combine to form a single product. Understanding these basic reaction types helps predict the outcomes when different elements interact with oxygen, leading to oxide formation.

The Process of Oxide Formation

Oxide formation is crucial in understanding reactions with oxygen. When elements react with oxygen, they often form stable oxides, which are compounds consisting of oxygen atoms bonded with other elements. The nature of the oxide depends on the element and the conditions under which the reaction occurs. For example, lithium forms lithium oxide (Li₂O) when it reacts with oxygen. The type of oxide formed can vary greatly, with some being acidic, basic, or amphoteric, affecting how they react with other substances. Oxide formation is a key aspect of many industrial processes and environmental phenomena.

Mastering Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It uses the balanced chemical equation to determine the proportions of substances involved. This is crucial in the given exercise, where equations for the reactions of elements with oxygen must be balanced. Each equation is balanced by ensuring that the number of atoms for each element is equal on both sides of the reaction. For example, in the reaction between aluminum and oxygen, the balanced equation is \(4Al + 3O_2 \rightarrow 2Al_2O_3\). Understanding stoichiometry allows chemists to predict the amounts of reactants needed and products formed, optimizing reactions for efficiency and desired outcomes.