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 \(\mathrm{HCl} .\)

Short answer

The balanced equations for the reactions of lithium with the given compounds are: 1. \(4 \space Li + O_{2} \rightarrow 2 \space Li_{2}O\) 2. \(2 \space Li + S \rightarrow Li_{2}S\) 3. \(2 \space Li + Cl_{2} \rightarrow 2 \space LiCl\) 4. \(12 \space Li + P_{4} \rightarrow 4 \space Li_{3}P\) 5. \(2 \space Li + H_{2} \rightarrow 2 \space LiH\) 6. \(2 \space Li + 2 \space H_{2}O \rightarrow 2 \space LiOH + H_{2}\) 7. \(2 \space Li + 2 \space HCl \rightarrow 2 \space LiCl + H_{2}\)

Step-by-step solution

1. Reaction with Oxygen (O₂)

Lithium reacts with oxygen to form lithium oxide (Li₂O). The unbalanced reaction is: \(Li + O_{2} \rightarrow Li_{2}O\) To balance the equation, we need 2 moles of lithium: \( 4 \space Li + O_{2} \rightarrow 2 \space Li_{2}O \)

2. Reaction with Sulfur (S)

Lithium reacts with sulfur to form lithium sulfide (Li₂S). The unbalanced reaction is: \(Li + S \rightarrow Li_{2}S\) To balance the equation, we need 2 moles of lithium: \(2 \space Li + S \rightarrow Li_{2}S\)

3. Reaction with Chlorine (Cl₂)

Lithium reacts with chlorine to form lithium chloride (LiCl). The unbalanced reaction is: \(Li + Cl_{2} \rightarrow LiCl\) To balance the equation, we need 2 moles of lithium chloride: \(2 \space Li + Cl_{2} \rightarrow 2 \space LiCl \)

4. Reaction with Phosphorus (P₄)

Lithium reacts with phosphorus to form lithium phosphide (Li₃P). The unbalanced reaction is: \(Li + P_{4} \rightarrow Li_{3}P\) To balance the equation, we need 12 moles of lithium and 4 moles of lithium phosphide: \(12 \space Li + P_{4} \rightarrow 4 \space Li_{3}P\)

5. Reaction with Hydrogen (H₂)

Lithium reacts with hydrogen to form lithium hydride (LiH). The unbalanced reaction is: \(Li + H_{2} \rightarrow LiH\) To balance the equation, we need 2 moles of lithium hydride: \(2 \space Li + H_{2} \rightarrow 2 \space LiH \)

6. Reaction with Water (H₂O)

Lithium reacts with water to form lithium hydroxide (LiOH) and hydrogen gas (H₂). The unbalanced reaction is: \(Li + H_{2}O \rightarrow LiOH + H_{2}\) To balance the equation, we need 2 moles of lithium, 2 moles of water, and 2 moles of lithium hydroxide: \(2 \space Li + 2 \space H_{2}O \rightarrow 2 \space LiOH + H_{2}\)

7. Reaction with Hydrochloric Acid (HCl)

Lithium reacts with hydrochloric acid to form lithium chloride (LiCl) and hydrogen gas (H₂). The unbalanced reaction is: \(Li + HCl \rightarrow LiCl + H_{2}\) To balance the equation, we need 2 moles of hydrochloric acid and 2 moles of lithium chloride: \(2 \space Li + 2 \space HCl \rightarrow 2 \space LiCl + H_{2}\)

Key concepts

Lithium Reactions

Lithium is a fascinating element because of its reactive nature. When it encounters different elements, it tends to form compounds rather quickly.
This behavior is crucial in various chemical equations and reactions.- With **Oxygen (O₂)**: Lithium forms lithium oxide (\(\text{Li}_2\text{O}\)). The balanced equation is:\[4 \text{Li} + \text{O}_2 \rightarrow 2 \text{Li}_2\text{O}\]- With **Sulfur (S)**: It forms lithium sulfide (\(\text{Li}_2\text{S}\)). The balanced equation is:\[2 \text{Li} + \text{S} \rightarrow \text{Li}_2\text{S}\]- With **Chlorine (Cl₂)**: This reaction results in lithium chloride (\(\text{LiCl}\)). The balanced equation is:\[2 \text{Li} + \text{Cl}_2 \rightarrow 2 \text{LiCl}\]These reactions highlight lithium's tendency to quickly combine with other elements to form stable compounds.

Stoichiometry

Stoichiometry is like the bookkeeping of chemistry. It ensures that you have the right amounts of reactants and products in a chemical reaction.
Understanding stoichiometry is key to balancing chemical equations effectively.- **Mole Ratios**: In stoichiometry, the coefficients in a balanced equation represent the ratios of moles of each substance involved in the reaction. For example, in \(4 \text{Li} + \text{O}_2 \rightarrow 2 \text{Li}_2\text{O}\), the ratio 4:1:2 tells us that 4 moles of lithium react with 1 mole of oxygen to produce 2 moles of lithium oxide.- **Conservation of Mass**: This principle states that the mass of the reactants equals the mass of the products. When balancing equations, this means ensuring that there are equal numbers of each type of atom on both sides of the reaction equation.Using stoichiometry efficiently requires practice but allows chemists to predict the quantities needed for any given chemical reaction.

Chemical Reactions

Chemical reactions involve the rearrangement of atoms to form new substances. They are represented by chemical equations, which are like recipes showing what you start with and finish with.- **Reactants and Products**: Reactants are the starting substances, and products are the end substances. For example, in the equation \(2 \text{Li} + \text{H}_2 \rightarrow 2 \text{LiH}\), lithium and hydrogen gas are the reactants, while lithium hydride is the product.- **Types of Reactions**: Reactions can be classified in various ways. For instance, lithium's reactions with water and hydrochloric acid (\(\text{HCl}\)) are examples of single replacement reactions. Another common type is synthesis reactions, like lithium reacting with oxygen or chlorine to form a single compound.Understanding the nature of the different types of chemical reactions helps in predicting the outcomes when different substances interact.

Reaction Balancing

Balancing chemical equations is all about keeping both sides of a reaction equal in terms of atoms. This is crucial for truly representing what happens during a chemical reaction.- **Steps to Balance Equations**: 1. **Write the Unbalanced Equation**: Identify all reactants and products. 2. **Count the Atoms on Each Side**: Ensure both sides have the same number of each type of atom. 3. **Adjust Coefficients**: Place numbers (called coefficients) in front of compounds to balance the atoms.For example, starting with the unbalanced equation \(\text{Li} + \text{P}_4 \rightarrow \text{Li}_3\text{P}\):- Count atoms: Li = 1 vs 3, P = 1 vs 4- Adjust to balance: \(12 \text{Li} + \text{P}_4 \rightarrow 4 \text{Li}_3\text{P}\)- **Re-check and Simplify**: Ensure atoms are balanced and the coefficients are in the simplest whole number ratio.Balancing is an essential skill to master, as it helps in understanding and predicting chemical reactions accurately.