Understanding the Chemical Reactions

Oct 13, 2025 by pynkocean.com 144 views

When One Mole of Each Substance is Burnt in Oxygen: Which Will Give the Largest Mass of CO₂?

In chemistry, combustion reactions involve the burning of a substance in oxygen to produce carbon dioxide (CO₂) and water (H₂O). The mass of CO₂ produced in a combustion reaction is directly related to the amount of carbon present in the original substance. In this article, we will compare the mass of CO₂ produced when one mole of each of the following substances is completely burnt in oxygen: Acetylene (C₂H₂), Diamond (C), Acetone (C₃H₆O), Benzene (C₆H₆), and Methane (CH₄).

Understanding the Chemical Reactions

Before we dive into the calculations, let's understand the chemical reactions involved in the combustion of each substance.

Acetylene (C₂H₂): 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
Diamond (C): C + O₂ → CO₂
Acetone (C₃H₆O): 2C₃H₆O + 9O₂ → 6CO₂ + 6H₂O
Benzene (C₆H₆): 2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O
Methane (CH₄): CH₄ + 2O₂ → CO₂ + 2H₂O

Calculating the Mass of CO₂ Produced

To calculate the mass of CO₂ produced in each reaction, we need to know the molar mass of CO₂, which is 44.01 g/mol. We also need to know the molar mass of each substance, which is:

Acetylene (C₂H₂): 26.04 g/mol
Diamond (C): 12.01 g/mol
Acetone (C₃H₆O): 58.08 g/mol
Benzene (C₆H₆): 78.11 g/mol
Methane (CH₄): 16.04 g/mol

Now, let's calculate the mass of CO₂ produced in each reaction.

Acetylene (C₂H₂): 2 mol C₂H₂ × 4 mol CO₂/mol C₂H₂ × 44.01 g/mol CO₂ = 352.08 g CO₂
Diamond (C): 1 mol C × 1 mol CO₂/mol C × 44.01 g/mol CO₂ = 44.01 g CO₂
Acetone (C₃H₆O): 2 mol C₃H₆O × 6 mol CO₂/mol C₃H₆O × 44.01 g/mol CO₂ = 1056.12 g CO₂
Benzene (C₆H₆): 2 mol C₆H₆ × 12 mol CO₂/mol C₆H₆ × 44.01 g/mol CO₂ = 2112.24 g CO₂
Methane (CH₄): 1 mol CH₄ × 1 mol CO₂/mol CH₄ × 44.01 g/mol CO₂ = 44.01 g CO₂

Based on the calculations, we can see that Benzene (C₆H₆) will produce the largest mass of CO₂ when one mole of each substance is completely burnt in oxygen. This is because Benzene has the highest molar mass among the five substances, and it produces the most CO₂ molecules per mole.

Comparison of the Results

Substance	Molar Mass (g/mol)	Mass of CO₂ Produced (g)
Acetylene (C₂H₂)	26.04	352.08
Diamond (C)	12.01	44.01
Acetone (C₃H₆O)	58.08	1056.12
Benzene (C₆H₆)	78.11	2112.24
Methane (CH₄)	16.04	44.01

In conclusion, when one mole of each of the following substances is completely burnt in oxygen, Benzene (C₆H₆) will produce the largest mass of CO₂. This is due to its high molar mass and the fact that it produces the most CO₂ molecules per mole.
Frequently Asked Questions (FAQs) About Combustion Reactions

Q: What is a combustion reaction?

A combustion reaction is a chemical reaction in which a substance reacts with oxygen to produce heat and light. In the context of this article, we are interested in the combustion reactions of Acetylene (C₂H₂), Diamond (C), Acetone (C₃H₆O), Benzene (C₆H₆), and Methane (CH₄).

Q: What is the difference between a combustion reaction and an oxidation reaction?

A combustion reaction is a specific type of oxidation reaction in which a substance reacts with oxygen to produce heat and light. However, not all oxidation reactions are combustion reactions. For example, the rusting of iron is an oxidation reaction, but it is not a combustion reaction.

Q: What is the role of oxygen in a combustion reaction?

Oxygen plays a crucial role in a combustion reaction. It is the reactant that combines with the fuel (the substance being burnt) to produce heat and light. In the absence of oxygen, a combustion reaction cannot occur.

Q: What is the significance of the molar mass of a substance in a combustion reaction?

The molar mass of a substance is a measure of the mass of one mole of that substance. In a combustion reaction, the molar mass of the substance determines the amount of CO₂ produced. Substances with higher molar masses produce more CO₂ per mole.

Q: Can you explain the concept of stoichiometry in a combustion reaction?

Stoichiometry is the study of the quantitative relationships between reactants and products in a chemical reaction. In a combustion reaction, stoichiometry is used to determine the amount of CO₂ produced from a given amount of fuel.

Q: What is the difference between a complete combustion reaction and an incomplete combustion reaction?

A complete combustion reaction is one in which the fuel is completely burnt to produce CO₂ and water. An incomplete combustion reaction is one in which the fuel is not completely burnt, resulting in the production of carbon monoxide (CO) and other pollutants.

Q: Can you give an example of a complete combustion reaction?

Yes, the combustion of methane (CH₄) is a complete combustion reaction:

CH₄ + 2O₂ → CO₂ + 2H₂O

Q: Can you give an example of an incomplete combustion reaction?

Yes, the combustion of methane (CH₄) in the presence of insufficient oxygen is an incomplete combustion reaction:

CH₄ + O₂ → CO + 2H₂

Q: What are the environmental implications of incomplete combustion reactions?

Incomplete combustion reactions can produce pollutants such as carbon monoxide (CO), particulate matter (PM), and volatile organic compounds (VOCs). These pollutants can have serious environmental and health implications.

Q: Can you summarize the key points of this article?

Yes, the key points of this article are:

Combustion reactions involve the burning of a substance in oxygen to produce CO₂ and water.
The molar mass of a substance determines the amount of CO₂ produced in a combustion reaction.
Benzene (C₆H₆) produces the largest mass of CO₂ when one mole of each substance is completely burnt in oxygen.
Incomplete combustion reactions can produce pollutants such as CO, PM, and VOCs.

In conclusion, combustion reactions are an important area of study in chemistry. Understanding the principles of combustion reactions can help us to better appreciate the environmental implications of these reactions and to develop strategies for reducing pollution.