Question

Write balanced equations describing the reaction of lithium metal with each of the following: ${\mathrm{O}}_2,\mathrm{S},{\mathrm{Cl}}_2,{\mathrm{P}}_4,{\mathrm{H}}_2,{\mathrm{H}}_2\mathrm{O},$ and HCl.

Short answer

The balanced equations for the reaction of lithium with the given substances are as follows: 1. $\mathrm{Li}+{\mathrm{O}}_2$: $$4\mathrm{Li}+{\mathrm{O}}_2\to 2{\mathrm{Li}}_2\mathrm{O}$$ 2. $\mathrm{Li}+\mathrm{S}$: $$2\mathrm{Li}+\mathrm{S}\to {\mathrm{Li}}_2\mathrm{S}$$ 3. $\mathrm{Li}+{\mathrm{Cl}}_2$: $$2\mathrm{Li}+{\mathrm{Cl}}_2\to 2\mathrm{Li}\mathrm{Cl}$$ 4. $\mathrm{Li}+{\mathrm{P}}_4$: $$12\mathrm{Li}+{\mathrm{P}}_4\to 4{\mathrm{Li}}_3\mathrm{P}$$ 5. $\mathrm{Li}+{\mathrm{H}}_2$: $$2\mathrm{Li}+{\mathrm{H}}_2\to 2\mathrm{Li}\mathrm{H}$$ 6. $\mathrm{Li}+{\mathrm{H}}_2\mathrm{O}$: $$2\mathrm{Li}+2{\mathrm{H}}_2\mathrm{O}\to 2\mathrm{Li}\mathrm{OH}+{\mathrm{H}}_2$$ 7. $\mathrm{Li}+\mathrm{H}\mathrm{Cl}$: $$2\mathrm{Li}+2\mathrm{H}\mathrm{Cl}\to 2\mathrm{Li}\mathrm{Cl}+{\mathrm{H}}_2$$

Step-by-step solution

Reaction with ${\mathrm{O}}_2$

Lithium reacts with oxygen to form lithium oxide (Li2O). The balanced equation is: $$4\mathrm{Li}+{\mathrm{O}}_2\to 2{\mathrm{Li}}_2\mathrm{O}$$

Reaction with $\mathrm{S}$

Lithium reacts with sulfur to form lithium sulfide (Li2S). The balanced equation is: $$2\mathrm{Li}+\mathrm{S}\to {\mathrm{Li}}_2\mathrm{S}$$

Reaction with ${\mathrm{Cl}}_2$

Lithium reacts with chlorine gas to form lithium chloride (LiCl). The balanced equation is: $$2\mathrm{Li}+{\mathrm{Cl}}_2\to 2\mathrm{Li}\mathrm{Cl}$$

Reaction with ${\mathrm{P}}_4$

Lithium reacts with white phosphorus (${\mathrm{P}}_4$) to form lithium phosphide (Li3P). The balanced equation is: $$12\mathrm{Li}+{\mathrm{P}}_4\to 4{\mathrm{Li}}_3\mathrm{P}$$

Reaction with ${\mathrm{H}}_2$

Lithium reacts with hydrogen to form lithium hydride (LiH). The balanced equation is: $$2\mathrm{Li}+{\mathrm{H}}_2\to 2\mathrm{Li}\mathrm{H}$$

Reaction with ${\mathrm{H}}_2\mathrm{O}$

Lithium reacts with water to form lithium hydroxide (LiOH) and hydrogen gas. The balanced equation is: $$2\mathrm{Li}+2{\mathrm{H}}_2\mathrm{O}\to 2\mathrm{Li}\mathrm{OH}+{\mathrm{H}}_2$$

Reaction with HCl

Lithium reacts with hydrochloric acid to form lithium chloride (LiCl) and hydrogen gas. The balanced equation is: $$2\mathrm{Li}+2\mathrm{H}\mathrm{Cl}\to 2\mathrm{Li}\mathrm{Cl}+{\mathrm{H}}_2$$

Key concepts

Lithium Reactions

Lithium, a soft and highly reactive alkali metal, takes part in numerous chemical reactions. It reacts vigorously with oxygen, forming lithium oxide, as the equation shows: $$4\text{Li}+{\text{O}}_2\to 2{\text{Li}}_2\text{O}$$This process highlights lithium’s strong affinity for oxygen and its ability to form stable oxides.
Another common reaction is with sulfur, yielding lithium sulfide:$$2\text{Li}+\text{S}\to {\text{Li}}_2\text{S}$$This indicates lithium's readiness to engage with non-metals, producing compounds known for their stability. When it comes to halogens like chlorine, lithium forms lithium chloride:$$2\text{Li}+{\text{Cl}}_2\to 2\text{Li}\text{Cl}$$Notably, this shows lithium's role in forming ionic compounds, characteristic of reactions involving halogens.
Further illustrating lithium's reactivity, it combines with white phosphorus:$$12\text{Li}+{\text{P}}_4\to 4{\text{Li}}_3\text{P}$$This reaction leads to lithium phosphide, emphasizing lithium’s capability to integrate with different molecular structures such as those of phosphorus.

Balancing Equations

Balancing chemical equations ensures that the law of conservation of mass is upheld in reactions. This involves making sure the number of each type of atom on the reactant side equals the number on the product side. When balancing, it's helpful to consider each element one by one.
For example, when balancing $4\text{Li}+{\text{O}}_2\to 2{\text{Li}}_2\text{O}$, check that both sides have the same tally for lithium and oxygen atoms. With four lithium atoms and two oxygen atoms on both sides, this equation meets the condition for balancing.
In reactions, lithium typically adopts a oxidation state of +1, affecting how equations are balanced when lithium is involved. Properly balancing reactions like $2\text{Li}+{\text{Cl}}_2\to 2\text{Li}\text{Cl}$ ensures that stoichiometric principles are followed and transformations occur as expected in experimental settings.

Inorganic Chemistry

Inorganic chemistry focuses on the study of inorganic compounds, which include most chemical reactions that do not involve carbon-hydrogen (C-H) bonds. Lithium reactions, like those with oxygen and sulfur, offer a perfect example of inorganic processes, resulting in compounds such as lithium oxide and lithium sulfide.
Beyond the formation of simple diatomic molecules, inorganic chemistry explores the interactions of metals with acids and water. In lithium's reaction with water:$$2\text{Li}+2{\text{H}}_2\text{O}\to 2\text{Li}\text{OH}+{\text{H}}_2$$the formation of lithium hydroxide (an inorganic compound) illustrates the complexities of chemical exchanges.

• This domain also covers the reactivity of metals, explaining phenomena like lithium's explosive interaction with hydrochloric acid, producing lithium chloride and hydrogen gas:

$$2\text{Li}+2\text{H}\text{Cl}\to 2\text{Li}\text{Cl}+{\text{H}}_2$$Understanding these principles forms the basis of much of inorganic chemistry and its practical applications.