Question

Complete and balance equations for the following reactions (the stoichiometry of each reaction is given in the equation).

Short answer

Answer: The balanced chemical equations for the example reactions are: 1. H2 + O2 → 2H2O 2. CH4 + 2O2 → CO2 + 2H2O 3. 4Fe + 3O2 → 2Fe2O3

Step-by-step solution

Identify the given reactions

First, we need to identify the given reactions to work with. Since the exercise doesn't provide any specific reactions to balance, it is difficult to provide a step-by-step solution without examples. However, let's consider the following example reactions: 1. H2 + O2 → H2O 2. CH4 + O2 → CO2 + H2O 3. Fe + O2 → Fe2O3 Now, let's balance these example equations.

Balance the first reaction (H2 + O2 → H2O)

We will balance the hydrogen and oxygen atoms in the given equation one by one. 1. Balance hydrogen: There are 2 hydrogen atoms on the left side and 2 on the right side, so hydrogen is already balanced. 2. Balance oxygen: There are 2 oxygen atoms on the left side and only 1 on the right side. We need to adjust the coefficient of H2O on the right side. So the balanced equation will be: H2 + O2 → 2H2O

Balance the second reaction (CH4 + O2 → CO2 + H2O)

We will balance the carbon, hydrogen, and oxygen atoms in the given equation one by one. 1. Balance carbon: There is 1 carbon atom on the left side and 1 on the right side, so carbon is already balanced. 2. Balance hydrogen: There are 4 hydrogen atoms on the left side and 2 on the right side. We need to adjust the coefficient of H2O on the right side. So the equation becomes: CH4 + O2 → CO2 + 2H2O 3. Balance oxygen: There are 2 oxygen atoms on the left side and 4 on the right side. We need to adjust the coefficient of O2 on the left side. So the balanced equation will be: CH4 + 2O2 → CO2 + 2H2O

Balance the third reaction (Fe + O2 → Fe2O3)

We will balance the iron and oxygen atoms in the given equation one by one. 1. Balance iron: There is 1 iron atom on the left side and 2 on the right side. We need to adjust the coefficient of Fe on the left side. So the equation becomes: 2Fe + O2 → Fe2O3 2. Balance oxygen: There are 2 oxygen atoms on the left side and 3 on the right side. We need to adjust the coefficients of O2 on the left side and Fe2O3 on the right side. So the balanced equation will be: 4Fe + 3O2 → 2Fe2O3 These are the balanced chemical equations for the example reactions given above.

Key concepts

Stoichiometry

Stoichiometry is the mathematical relationship between the quantities of reactants and products in a chemical reaction. It is like a recipe for chemistry, providing the proportions of each substance involved. The central principle of stoichiometry is the law of conservation of mass, which states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products.

For students to master stoichiometry, you need to understand how to read a chemical equation and identify the moles of each substance. A mole is a unit of measurement used to express amounts of a chemical substance. When balancing equations, students are essentially ensuring that the number of moles of the reactants equals the number of moles of the products.

Improvement advice for exercises involving stoichiometry includes hands-on activities that involve measuring and predicting the amounts of reactants and products, and using visual aids like the periodic table and molecular models to better understand the concept of moles and molar ratios.

Chemical Reaction

A chemical reaction involves the transformation of one set of chemical substances to another. Through the breaking and forming of bonds, atoms are reorganized into new molecules. To comprehend chemical reactions, it's important to recognize reactants, which are the starting substances, and products, which are the substances formed as a result of the reaction.

Indicators of chemical reactions can include a change in color, temperature, the formation of a precipitate, or the evolution of gas. However, to truly confirm a chemical reaction, the chemical identity of the substances must change, which is underscored through balanced chemical equations.

By incorporating visuals and simulations showing the rearrangement of atoms during a reaction, students can better visualize the process. Demonstrations in the laboratory setting also enhance understanding by allowing students to observe reactions firsthand.

Molecular Coefficients

In the context of a balanced chemical equation, molecular coefficients refer to the numbers placed in front of compounds to indicate the ratio of molecules or moles of each substance involved in the reaction. These coefficients are critical because they ensure that the law of conservation of mass is followed, as well as the conservation of atoms of each element.

Understanding how to manipulate these coefficients is essential when balancing equations. They tell you how many units of each substance you need to satisfy the requirements of the chemical reaction. For instance, in the balanced equation \(2Fe + 3O2 \rightarrow 2Fe2O3\), the coefficient \(2\) in front of \(Fe\) signifies that two moles of iron react with three moles of oxygen to form two moles of iron(III) oxide.

Teaching tips for mastering molecular coefficients include using ratio and proportion exercises to get familiar with the concept, as well as practice exercises where students balance equations with varying levels of complexity.