Question

Write a balanced equation for the reaction of hydrogen and oxygen gases.

Short answer

The balanced equation is \( 2H_2 + O_2 \rightarrow 2H_2O \).

Step-by-step solution

Identify Molecular Formulas

Identify the molecular formulas for the reactants and products. Hydrogen gas is represented by \( H_2 \), and oxygen gas is represented by \( O_2 \). The product is water, which is represented by \( H_2O \).

Write the Unbalanced Equation

Write the unbalanced chemical equation using the chemical formulas from Step 1: \( H_2 + O_2 \rightarrow H_2O \).

Balance Hydrogen Atoms

There are 2 hydrogen atoms on the left side in \( H_2 \) and 2 hydrogen atoms in one \( H_2O \) molecule on the right side. The number of hydrogen atoms is already balanced.

Balance Oxygen Atoms

There are 2 oxygen atoms on the left side in \( O_2 \), but only 1 oxygen atom in one \( H_2O \) on the right side. To balance, place a coefficient of 2 before \( H_2O \) to get \( 2H_2O \), providing 2 oxygen atoms on the right: \( H_2 + O_2 \rightarrow 2H_2O \).

Rebalance Hydrogen If Needed

Now there are 4 hydrogen atoms on the right (from \( 2H_2O \)) but only 2 hydrogen atoms on the left in \( H_2 \). To balance, place a coefficient of 2 before \( H_2 \): \( 2H_2 + O_2 \rightarrow 2H_2O \).

Verify the Balanced Equation

Check to ensure both sides of the equation have the same number of each type of atom. On both sides, there are 4 hydrogen atoms (from \( 2H_2 \)) and 2 oxygen atoms (from \( O_2 \) and \( 2H_2O \)), confirming the equation is balanced.

Key concepts

Balancing Chemical Equations

Balancing chemical equations is a crucial skill in chemistry. It ensures that the same number of each type of atom is present on both sides of the equation, reflecting the conservation of mass. A balanced equation adheres to the law of conservation of mass, which states that in a chemical reaction, matter is not created or destroyed. To balance an equation:

• Identify each type of atom in the reactants and products.
• Count the number of atoms of each type on both sides.
• Use coefficients to adjust the number of molecules, ensuring an equal number of each type of atom on both sides.

For example, in the equation for the reaction of hydrogen and oxygen to form water, you start with the unbalanced equation: \[ H_2 + O_2 \rightarrow H_2O \]Initially, hydrogen is balanced with 2 atoms on each side. However, oxygen is unbalanced. By placing a coefficient of 2 before \( H_2O \), both sides have 2 oxygen atoms:\[ H_2 + O_2 \rightarrow 2H_2O \]Then, rebalance the hydrogen by adjusting its coefficient, resulting in a balanced equation:\[ 2H_2 + O_2 \rightarrow 2H_2O \] It's essential to double-check your balance by verifying each type of atom has the same count on both sides.

Reaction of Hydrogen and Oxygen

The reaction of hydrogen and oxygen gases to form water is a classic example of a chemical reaction. Both hydrogen and oxygen are diatomic molecules, meaning each is made up of two atoms. The reactants—hydrogen gas \( H_2 \) and oxygen gas \( O_2 \)—combine to form water \( H_2O \). This reaction is not only fundamental in chemistry but is also essential in various applications, including fuel cells and rocket propulsion.Understanding this reaction:

• The reactants \( H_2 \) and \( O_2 \) are both gases, making them challenging to observe directly without a reaction.
• When ignited, hydrogen and oxygen react explosively to form water, releasing energy in the process, making it an exothermic reaction.
• The balanced chemical equation \( 2H_2 + O_2 \rightarrow 2H_2O \) demonstrates the stoichiometry—showing that each oxygen molecule reacts with two hydrogen molecules to produce two molecules of water.

This reaction is a key example of how energy can be released in chemical transformations, highlighting the transformation of reactant molecules into product molecules.

Molecular Formulas

Molecular formulas are crucial to understanding chemical reactions. They provide the simplest detail of the actual molecules involved, showing the exact number and type of atoms in a molecule. With molecular formulas, it's easier to grasp the components that participate in reactions. For example:

• Hydrogen gas is represented as \( H_2 \), indicating that each molecule consists of two hydrogen atoms.
• Oxygen gas is expressed as \( O_2 \), with each molecule comprising two oxygen atoms.
• Water, the product of the hydrogen-oxygen reaction, is represented as \( H_2O \), consisting of two hydrogen atoms and one oxygen atom per molecule.

Molecular formulas play a crucial role in the process of balancing equations. By understanding what molecules are involved, chemists can write correct unbalanced equations, then balance them to accurately represent the conservation of mass in chemical reactions. They serve as a foundational tool for anyone learning chemistry, providing a stepping stone to more advanced topics like molecular structure and chemical bonding.