Question

Give three examples of emissions from complete combustion.

Short answer

Question: Provide three examples of emissions from complete combustion. Answer: Three examples of emissions from complete combustion include: 1. Carbon dioxide (CO2) and water (H2O) produced during the complete combustion of methane (CH4). 2. Carbon dioxide (CO2) and water (H2O) produced during the complete combustion of propane (C3H8). 3. Carbon dioxide (CO2) and water (H2O) produced during the complete combustion of octane (C8H18).

Step-by-step solution

Understand Complete Combustion

Complete combustion occurs when a fuel burns in a sufficient and well-mixed supply of oxygen, converting the fuel entirely to carbon dioxide (CO2) and water (H2O). This process releases the maximum amount of energy from the fuel. Common fuels that undergo combustion include hydrocarbons, such as propane, natural gas, and gasoline.

Identify Typical Emissions from Complete Combustion

The two main emissions from complete combustion are carbon dioxide (CO2) and water (H2O). In addition, smaller amounts of other gases and particles may also be produced, depending on the fuel and combustion conditions.

Example 1: Complete Combustion of Methane (CH4)

Methane, a common component of natural gas, undergoes complete combustion according to the following balanced chemical equation: CH4 + 2O2 -> CO2 + 2H2O Here, methane reacts with oxygen (O2), producing carbon dioxide (CO2) and water (H2O) as emissions.

Example 2: Complete Combustion of Propane (C3H8)

Propane, a fuel commonly used for heating and cooking, undergoes complete combustion according to the following balanced chemical equation: C3H8 + 5O2 -> 3CO2 + 4H2O In this case, propane reacts with oxygen (O2), resulting in emissions of carbon dioxide (CO2) and water (H2O).

Example 3: Complete Combustion of Octane (C8H18)

Octane, a primary component of gasoline, undergoes complete combustion according to the following balanced chemical equation: C8H18 + 12.5O2 -> 8CO2 + 9H2O Here, octane reacts with oxygen (O2), producing emissions of carbon dioxide (CO2) and water (H2O).

Key concepts

Carbon Dioxide (CO2)

Carbon dioxide, or CO2, is a key player in the world of emissions. Whenever complete combustion occurs, CO2 is one of the primary products. During combustion, carbon atoms from the fuel oxidize, forming carbon dioxide. This is what happens when we burn fossil fuels like coal, oil, and natural gas. These are rich in hydrocarbons. CO2 is recognized for its role as a greenhouse gas. This means it traps heat in the atmosphere, contributing to global warming. Despite being necessary for photosynthesis, excessive CO2 in the atmosphere can have negative environmental effects.

• CO2 results from complete combustion, when there is enough oxygen for all carbon to become CO2.
• It plays a role in sustaining life by being part of the carbon cycle.
• Excessive emissions can lead to climate change.

Methane Combustion

Methane, with the chemical formula CH4, is a simple hydrocarbon and a major component of natural gas. During complete combustion of methane, it reacts with oxygen, forming carbon dioxide and water:\[ \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} \]This process is highly efficient, meaning that it produces maximum energy. Consequently, methane is a valuable fuel source. Methane combustion is favored in applications where clean and efficient energy is needed, such as cooking and heating.

• Methane burns completely when there is sufficient oxygen.
• The main emissions from this process are carbon dioxide and water vapor.
• It is crucial in reducing the use of "dirtier" fuels that produce more pollutants.

Chemistry Equations

Chemistry equations are symbolic representations of chemical reactions. They show us what substances interact, the products formed, and the proportion in which they react. In the case of complete combustion, such equations help us understand how hydrocarbons react with oxygen.A balanced chemical equation is important. It shows the conservation of mass during the reaction, meaning the number of atoms for each element is the same on both sides of the equation. Take methane’s combustion as an example:\[ \text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O} \]Here, every molecule of methane reacts with two molecules of oxygen to yield a molecule of CO2 and two of water. These equations are crucial for scientists and engineers as they design processes involving combustion.

• The coefficients denote how many molecules of each substance are involved.
• Equations must be balanced to accurately represent the reaction.
• They help predict the amount of each product formed from a given amount of reactant.