Question

Write a chemical equation for magnesium metal combining with bromine liquid to give magnesium bromide solid.

Short answer

The balanced equation is: Mg (s) + Br₂ (l) → MgBr₂ (s).

Step-by-step solution

Start with Reactants

Identify the reactants in this reaction. We are dealing with magnesium metal (Mg) and bromine liquid (Br₂). These will be on the left side of the equation.

Identify the Products

The product of this reaction is magnesium bromide, which is a solid. In chemical notation, we write it as MgBr₂ (solid). It will be on the right side of the equation.

Write Initial Chemical Equation

Start assembling the chemical equation with the identified reactants and products: Mg (s) + Br₂ (l) → MgBr₂ (s). Ensure that states of matter are indicated: (s) for solid, (l) for liquid, and (g) for gas.

Balance the Chemical Equation

Count the number of each type of atom on both sides of the equation. Currently, there are 2 bromines in Br₂ but only 1 in MgBr₂. Adjust the product side to make sure it reflects the balancing requirement: Mg (s) + Br₂ (l) → MgBr₂ (s). Each side of the equation now has: 1 Mg and 2 Br atoms, hence it is balanced.

Key concepts

Reactants and Products

In a chemical reaction, the substances present at the beginning are called reactants. They undergo a transformation during the reaction. For the given chemical scenario, the reactants are magnesium metal (Mg) and bromine liquid (Br₂). These reactants are combined in a chemical reaction to form new substances, known as products. In this case, the single product generated is magnesium bromide (MgBr₂), which is a solid.

When expressing these substances in a chemical equation, reactants are placed on the left-hand side, typically highlighted by a plus sign if more than one reactant is involved. Products, on the other hand, are shown on the right-hand side, often connected by an arrow to indicate that they are the result of the reaction of the reactants.

• Reactants: Magnesium (Mg) and Bromine (Br₂)
• Product: Magnesium Bromide (MgBr₂)

Understanding the function of reactants and products in a chemical equation provides clarity on how chemical transformations take place. It also lays the foundation to solve and balance such equations effectively.

Balancing Equations

A balanced chemical equation has equal numbers of each type of atom on both sides of the equation. Balancing is necessary to obey the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction.

In the given exercise, the initial unbalanced equation is:$$\text{Mg (s)}+{\text{Br}}_2\text{ (l)}\to {\text{MgBr}}_2\text{ (s)}$$This equation correctly lists the reactants and products, but does not initially display the same number of each type of atom on both sides. Specifically, there are 2 bromine atoms in the reactant Br₂ but only 1 bromine atom in the product MgBr₂. By inspecting the equation, we can add a coefficient of 1 in front of MgBr₂ (which effectively leaves it unchanged, because coefficients equal to 1 are implied) to confirm the presence of two bromine atoms. This results in a balanced equation where both sides exhibit one magnesium atom and two bromine atoms each:

1. Count the number of atoms for each element in the reactants and products. - Magnesium: 1 on both sides - Bromine: 2 on both sides2. Adjust coefficients if necessary (in this case, no change was needed because MgBr₂ naturally contains the right amount once paired with Br₂).

• Balancing ensures the conservation of mass and verifies that all quantities are rightfully accounted for in the chemical equation.

States of Matter

When writing chemical equations, indicating the state of matter for each reactant and product provides essential context. The states of matter include solid (s), liquid (l), gas (g), and aqueous (aq) for substances dissolved in water.

In our chemical equation for the reaction between magnesium and bromine:$$\text{Mg (s)}+{\text{Br}}_2\text{ (l)}\to {\text{MgBr}}_2\text{ (s)}$$- **Magnesium (Mg)** is listed as a solid (s) because it is naturally found in this state at room temperature.- **Bromine (Br₂)** is a liquid (l), one of few elements that are liquid under standard conditions.- **Magnesium Bromide (MgBr₂)** is the product appearing as a solid (s), typical for ionic compounds formed by a metal and a non-metal.

Including states of matter in chemical equations allows chemists to better predict the physical behavior and changes in a reaction, thus providing a more complete picture of the reaction environment and outcome.