G2 Gas Fitter Practice Exam

What are the primary products of complete combustion of a hydrocarbon?

1. Carbon monoxide and soot

2. Water and carbon dioxide

3. Hydrogen gas and nitrogen

4. Ozone and methane

The correct answer is: Water and carbon dioxide

The primary products of complete combustion of a hydrocarbon are water and carbon dioxide. During complete combustion, hydrocarbons react with an adequate supply of oxygen, resulting in the breakdown of the carbon and hydrogen atoms in the hydrocarbon molecule. When a hydrocarbon burns completely, every carbon atom bonds with oxygen to form carbon dioxide, while every two hydrogen atoms bond with oxygen to create water. This process releases a significant amount of energy in the form of heat and light, which is why combustion is often used as an energy source in engines and heating systems. Complete combustion ideally occurs when there's enough oxygen available. In contrast, if there is insufficient oxygen, incomplete combustion may happen, producing byproducts such as carbon monoxide and soot, rather than solely water and carbon dioxide. Understanding this concept is crucial for gas fitters, as it impacts the efficiency and safety of combustion appliances.