Question

Gasoline contains only hydrogen and carbon atoms. Yct nitrogen oxide and nitrogen dioxide are produced when gasoline burns. What is the source of the nitrogen and oxygen atoms?

Short answer

Nitrogen and oxygen atoms come from atmospheric air.

Step-by-step solution

Understanding Combustion

When gasoline burns, it undergoes a chemical reaction known as combustion. This reaction typically involves reacting with oxygen, usually from the air, resulting in the production of various gases.

Composition of Atmospheric Air

Atmospheric air is primarily composed of approximately 78% nitrogen, 21% oxygen, and lesser amounts of other gases. These gases play a crucial role during the combustion of gasoline.

Formation of Nitrogen Oxides

During combustion at high temperatures, nitrogen from the air can react with oxygen from the air to form nitrogen oxides like nitrogen monoxide (NO) and nitrogen dioxide (NO₂).

Source of Nitrogen and Oxygen

The nitrogen and oxygen atoms in nitrogen oxides come from the nitrogen and oxygen present in the atmospheric air involved in the combustion process.

Key concepts

Combustion

Combustion is a chemical reaction that occurs when a substance burns in the presence of oxygen. In the case of gasoline, which is primarily composed of carbon and hydrogen, the reaction releases energy in the form of heat and light. This is why engines and other machinery can run on gasoline, as the energy released during combustion can be harnessed for movement or other functions.
In general, the reaction can be summarized as follows:

• Fuel (hydrocarbons) + Oxygen → Carbon Dioxide + Water + Energy

This process also often forms other by-products, depending on the conditions, such as incomplete gas burn, temperature, and presence of other elements in the air.

Atmospheric Composition

The atmosphere is a mixture of different gases that surrounds the Earth and is crucial for life and various natural processes, including combustion. The main components of atmospheric air include:

• Nitrogen (78%)
• Oxygen (21%)
• Trace gases like argon and carbon dioxide make up the remaining percentage.

These components are essential not only for breathing but also for combustion processes. The oxygen in the atmosphere helps fuels to ignite and continue to burn, while the nitrogen, although generally inert, can participate in reactions under specific conditions.

Nitrogen Oxides

Nitrogen oxides, often abbreviated as NOx, are significant pollutants that are primarily produced during the combustion process. When fuels burn at high temperatures, the nitrogen present in the air can combine with oxygen to form various compounds such as nitrogen monoxide (NO) and nitrogen dioxide (NO₂).
The formation equation can be expressed as:

• \[N_2 + O_2 ightarrow 2NO\]

These reactions typically occur in car engines, power plants, and other industrial processes. Nitrogen oxides have various environmental effects, including contributing to smog and acid rain, which can impact both human health and the environment.

Nitrogen and Oxygen Sources

In any combustion process, the primary source of nitrogen and oxygen is the atmospheric air itself. When gasoline combusts, it does not only involve the burning of carbon and hydrogen but also engages the air surrounding it.
The presence of oxygen is vital to sustain combustion, but when it comes to nitrogen oxides, the nitrogen used is sourced from the air too. Although nitrogen is relatively inert, the high heat of combustion processes allows it to react with oxygen and form the nitrogen oxides seen as by-products of gasoline burning. Therefore, understanding the roles these atmospheric gases play is vital in analyzing combustion reactions and their environmental impacts.