Question

Acetylene gas \(\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)\) is often used by plumbers, welders, and glass blowers because it burns in oxygen with an intensely hot flame. The products of the combustion of acetylene are carbon dioxide and water vapor. Write the unbalanced chemical equation for this process.

Short answer

The balanced chemical equation for the combustion of acetylene gas (C2H2) in the presence of oxygen (O2) is: \(2C_2H_2 + 5O_2 → 4CO_2 + 4H_2O\)

Step-by-step solution

Write the reactants and products.

In the given exercise, we know that the reactants are acetylene gas (C2H2) and oxygen gas (O2). The products of this reaction are carbon dioxide (CO2) and water vapor (H2O). Combustion reaction usually takes the form: Reactants → Products So, the initial unbalanced chemical equation will look like this: C2H2 + O2 → CO2 + H2O

Balance the chemical equation.

Now, we will balance the chemical equation by making sure the same number of atoms of each element are present on both sides of the equation. 1. Carbon atoms: There are 2 carbon atoms in C2H2 and only 1 carbon atom in CO2. Thus, we need to put a 2 in front of CO2. C2H2 + O2 → 2CO2 + H2O 2. Hydrogen atoms: There are 2 hydrogen atoms in C2H2 and 2 hydrogen atoms in H2O. So the hydrogen atoms are already balanced. 3. Oxygen atoms: There are 2 oxygen atoms in O2, 4 oxygen atoms in 2CO2, and 1 oxygen atom in H2O. To balance the oxygen atoms, we will put a 2 in front of H2O and 2.5 in front of O2. C2H2 + 2.5O2 → 2CO2 + 2H2O However, it's not recommended to have fractions in a balanced chemical equation. We can get rid of the fraction by multiplying every coefficient by 2. 2C2H2 + 5O2 → 4CO2 + 4H2O Now, the chemical equation is balanced, with 4 carbon atoms, 8 hydrogen atoms, and 10 oxygen atoms on both sides of the equation.

Final Balanced Chemical Equation

The balanced chemical equation for the combustion of acetylene gas (C2H2) in the presence of oxygen (O2) is as follows: 2C2H2 + 5O2 → 4CO2 + 4H2O

Key concepts

Combustion Reaction

Combustion reactions are a type of chemical reaction where a substance reacts rapidly with oxygen, producing heat and light. This process is exothermic, meaning it releases energy in the form of heat. Generally, combustion involves organic compounds (compounds that contain carbon and hydrogen) reacting with oxygen in the air.

Here are some key features of combustion reactions:

• Products: Commonly produce carbon dioxide and water.
• Type of Reaction: Usually considered oxidation reactions.
• Energy Release: Capable of releasing large amounts of energy as heat and light.

Combustion reactions are crucial in daily life. They provide energy for heating, electricity, and transportation.

Acetylene Combustion

Acetylene combustion is a specific type of combustion reaction. It involves the burning of acetylene (\(\mathrm{C}_{2} \mathrm{H}_{2}\)) in oxygen, which is commonly used due to its intensely hot flame. This makes acetylene ideal for use by welders, plumbers, and glass blowers.

During the combustion of acetylene, the chemical reaction produces carbon dioxide (\(\mathrm{CO}_{2}\)) and water (\(\mathrm{H}_{2}\mathrm{O}\)) as products. The reaction can be represented by the unbalanced equation:

\[ \mathrm{C}_2 \mathrm{H}_2 + \mathrm{O}_2 \rightarrow \mathrm{CO}_2 + \mathrm{H}_2 \mathrm{O} \]

To ensure the same number of atoms on both sides, the equation must be balanced. This involves adjusting coefficients to account for all carbon, hydrogen, and oxygen atoms present in the reactants and products.

Stoichiometry

Stoichiometry is the branch of chemistry that focuses on the quantitative relationships between the amounts of reactants used and products formed during chemical reactions. It is an essential tool for chemists because it helps in predicting the quantities of substances consumed and created.

When balancing a chemical equation, stoichiometry is used to determine the correct proportions of reactants and products. It involves ensuring that the number of atoms for each element is the same on both sides of the chemical equation. This is required because of the law of conservation of mass, which states that mass cannot be created or destroyed in a chemical reaction.

Consider the balanced chemical equation for acetylene combustion:

• 4 carbon atoms on both sides
• 8 hydrogen atoms on both sides
• 10 oxygen atoms on both sides

Understanding stoichiometry allows you to balance chemical equations and anticipate how much of a product can be generated from given amounts of reactants.