Chemistry Regents Practice Test 2025 – Complete Prep Resource

The primary product of the combustion of hydrocarbons is carbon dioxide. When hydrocarbons, which are compounds made up of hydrogen and carbon atoms, undergo combustion, they react with oxygen. This reaction can be represented by a general equation:

\[ \text{Hydrocarbon} + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} \]

In a complete combustion reaction, a hydrocarbon burns in the presence of sufficient oxygen, resulting in the formation of carbon dioxide and water. Carbon dioxide is produced as the carbon atoms in the hydrocarbon are oxidized.

While water is also produced, carbon dioxide is typically considered the primary product in the context of environmental and energy discussions, especially because it is a significant greenhouse gas with implications for climate change. Oxygen is not produced in combustion; rather, it is consumed, while carbon monoxide may occur as a byproduct under certain incomplete combustion conditions, but it is not the primary product when combustion occurs efficiently. Therefore, carbon dioxide is the most prominent and recognized product of complete hydrocarbon combustion.