Problem 70 - Chemistry Matter and Change

Question

Write a skeleton equation for the reaction between lithium(s) and chlorine gas to produce lithium chloride(s).

Step-by-Step Solution

Answer

The balanced skeleton equation for the reaction between lithium (s) and chlorine gas to produce lithium chloride (s) is: \(2Li(s) + Cl_2(g) \rightarrow 2LiCl(s)\).

Step 1: Identify the reactants and products

The reactants are lithium (Li, solid) and chlorine gas (Cl₂, gas). The product is lithium chloride (LiCl, solid).

Step 2: Write down their symbols and states

Lithium: Li(s) - solid Chlorine gas: Cl₂(g) - gas Lithium chloride: LiCl(s) - solid The unbalanced equation would be: Li(s) + Cl₂(g) → LiCl(s)

Step 3: Balance the equation

To balance the equation, we will ensure that the number of atoms for each element is equal on both sides of the equation. Li(s) + Cl₂(g) → LiCl(s) On the left side (reactants), we have 1 Li atom and 2 Cl atoms. On the right side (products), we have 1 Li atom and 1 Cl atom. To balance the number of Cl atoms, we will need 2 LiCl molecules on the right side: Li(s) + Cl₂(g) → 2LiCl(s) Now we have 2 Li atoms and 2 Cl atoms on the right side. We need to add another Li atom on the left side to balance the Li atoms. We do this by placing a coefficient of 2 in front of Li: 2Li(s) + Cl₂(g) → 2LiCl(s) Now the equation is balanced with 2 Li atoms and 2 Cl atoms on both sides.

Key Concepts

Balancing Chemical Equations

Chemical reactions involve the transformation of reactants into products, following specific stoichiometry rules. Balancing a chemical equation ensures that the same number of each type of atom appears on both sides of the equation. This is crucial because, according to the law of conservation of mass, matter cannot be created or destroyed in a chemical reaction. To balance a chemical equation:

• Identify each element present in the reactants and products.
• Count the number of atoms of each element on both sides of the equation.
• Add coefficients (numbers placed before compounds) to balance the number of atoms for each element on both sides.

Consider the example: 2Li(s) + Cl₂(g) → 2LiCl(s). Here, the equation is balanced by adding a coefficient of 2 in front of both lithium on the left side and lithium chloride on the right, ensuring there are 2 lithium and 2 chlorine atoms on each side of the reaction.

Skeleton Equation

A skeleton equation provides a starting point for writing chemical equations. It shows the reactants and products involved but does not indicate their amounts. Essentially, it highlights the chemical formulas and phases of each substance. The skeleton equation is helpful because it sets up the framework needed to balance a chemical equation. For example, in the reaction between lithium and chlorine gas to form lithium chloride, the skeleton equation is: Li(s) + Cl₂(g) → LiCl(s) This equation outlines the reactants (Li and Cl₂) and the product (LiCl), including their physical states efficiently, paving the way to balance the equation further as needed. Starting with a skeleton equation simplifies the process of balancing as it clearly identifies all participating chemicals.

Reactants and Products Identification

Identifying reactants and products is a critical step in writing chemical equations. Reactants are substances initially present before a chemical reaction occurs, while products are substances formed as a result of the reaction. In a chemical equation:

• Reactants are listed on the left side.
• Products are listed on the right side.
• An arrow (→) separates reactants and products, indicating the direction of the reaction.

For instance, in the equation Li(s) + Cl₂(g) → LiCl(s), lithium (Li) and chlorine gas (Cl₂) are the reactants. They react to form lithium chloride (LiCl), the product. Clear identification of reactants and products is essential for anyone studying chemical reactions as it builds a foundation for understanding more complex reactions and balancing equations.