Aside from the production of carbon monoxide and soot, burning alkanes has several other environmental consequences. One of the major concerns is the emission of carbon dioxide, a greenhouse gas, which contributes to global warming and climate change. The combustion of alkanes, like all fossil fuels, is a significant source of carbon dioxide emissions. Additionally, nitrogen oxides (NOx) can also be produced, especially in high-temperature combustion processes. These nitrogen oxides are pollutants that contribute to smog and acid rain and can have adverse effects on respiratory health. Furthermore, the release of particulate matter (PM), which includes a range of tiny particles and droplets, can also occur. These particles can penetrate deep into the lungs and are linked to health problems like heart and lung diseases. Moreover, the extraction, processing, and transportation of alkanes as fuels also pose environmental risks, including oil spills, habitat destruction, and water pollution. These broader impacts highlight the need for sustainable and cleaner energy sources to mitigate the environmental footprint of alkane combustion.

Alkanes predominantly undergo combustion reactions due to their chemical structure and properties. Alkanes are saturated hydrocarbons with single bonds between carbon atoms, making them relatively stable and unreactive compared to other organic compounds like alkenes or alkynes. However, they have significant potential energy stored in the C-H and C-C bonds. When exposed to heat and an oxidiser (typically oxygen in air), this potential energy can be released as heat and light, leading to combustion. The simplicity of alkanes means they lack functional groups that would typically facilitate other types of chemical reactions. As such, combustion, which involves the breaking of C-H and C-C bonds and the formation of new bonds with oxygen, becomes the primary reaction pathway for alkanes, especially under conditions where heat and oxygen are present. This characteristic makes alkanes ideal as fuels, where the primary goal is the release of energy through combustion.

Temperature plays a critical role in the combustion of alkanes. It affects both the rate of reaction and the type of combustion (complete or incomplete) that occurs. For combustion to initiate, the alkane must reach its ignition temperature, the minimum temperature required to start combustion. Once the reaction starts, if the temperature is sufficiently high and oxygen is abundant, complete combustion is more likely to occur, leading to the formation of carbon dioxide and water. Conversely, at lower temperatures, especially when oxygen supply is limited, incomplete combustion becomes more probable, resulting in the production of carbon monoxide and soot. The higher the temperature, the faster the combustion reaction proceeds, as increased temperature provides the reactant molecules with more kinetic energy. This heightened energy leads to more frequent and effective collisions among reactant molecules, thereby increasing the rate of reaction. In industrial applications, controlling the temperature is crucial for achieving efficient and safe combustion of alkanes.

The presence of impurities in alkanes can significantly affect their combustion process, primarily influencing the efficiency and cleanliness of the reaction. Common impurities in alkanes include sulfur compounds, nitrogen compounds, and trace metals. Sulfur impurities, when combusted, produce sulfur dioxide (SO2), a toxic gas that contributes to acid rain and respiratory problems. Similarly, nitrogen impurities can form nitrogen oxides (NOx), which are harmful pollutants. Trace metals present in alkanes can lead to the formation of metal oxides, which may cause problems in combustion engines and industrial burners by fouling equipment. Additionally, impurities can lower the fuel's calorific value, meaning more fuel is required to produce the same amount of energy, leading to increased emissions. Therefore, the purification of alkanes, typically through refining processes, is crucial to ensure efficient, clean, and safe combustion. This purification process removes most of the impurities, improving the quality of the fuel and reducing the environmental impact of its combustion.

The structure of an alkane significantly influences its combustion reaction, particularly in terms of the ease of ignition and the amount of energy released. Straight-chain alkanes tend to have higher boiling points and are less volatile compared to their branched counterparts. This means that straight-chain alkanes require more energy to initiate combustion. However, once ignited, they typically burn more steadily. Branched alkanes, on the other hand, have lower boiling points and are more volatile, making them easier to ignite. The combustion of alkanes also varies with the length of the carbon chain. Shorter alkanes combust more readily than longer ones due to the lower activation energy required for the combustion reaction. Longer alkanes, although they burn less readily, release more energy upon combustion because they contain more carbon and hydrogen atoms to oxidise. Therefore, the structure – both in terms of branching and chain length – is a crucial factor in determining the combustion characteristics of alkanes.