I'm an expert in the field of chemistry and fuels, and I'm here to provide you with a detailed explanation on what ignites gasoline.

Gasoline, also known as petrol, is a complex mixture of hydrocarbons that are derived from crude oil. It is a highly flammable liquid that is used as fuel in internal combustion engines. The ignition of gasoline is a complex process that involves several key factors and components.

Firstly, it's important to understand that gasoline is a volatile substance. This means that it can evaporate quickly at room temperature, releasing its flammable vapors into the air. The vapors are a mixture of various hydrocarbons, which are compounds made up of hydrogen and carbon atoms. These hydrocarbons are what make gasoline so reactive and capable of igniting.

The flash point of gasoline is a critical temperature at which the vapors that evaporate from the liquid can ignite in the presence of an ignition source, such as a spark or flame. The flash point for gasoline is quite low, around -50°F (-65°C), which means it can ignite under a wide range of conditions.

The ignition temperature, on the other hand, is the temperature at which gasoline will ignite without the need for an external ignition source. For gasoline, this temperature is approximately 495°F (232°C). However, it's important to note that this is a theoretical value, and in practice, gasoline will ignite at lower temperatures when mixed with air and exposed to a spark or flame.

The process of igniting gasoline involves the following steps:


1. Vaporization: Gasoline must first evaporate to form a mixture of flammable vapors with air. This occurs when the liquid gasoline is heated, either by the engine's heat or by external sources.


2. Mixture Formation: The vaporized gasoline mixes with air to form a combustible mixture. The ideal air-fuel ratio for gasoline is about 14.7 parts air to 1 part fuel by mass, known as the stoichiometric ratio.


3. Ignition: The mixture of gasoline vapor and air must reach a certain temperature or be exposed to an ignition source to ignite. In an engine, this is typically achieved through the spark from a spark plug.


4. Combustion: Once ignited, the gasoline undergoes a rapid combustion reaction, releasing energy in the form of heat and light. This energy is what powers the engine.


5. Exhaust: The combustion process produces exhaust gases, which are expelled from the engine.

It's also worth mentioning that gasoline contains additives to improve its performance and stability. These additives can affect the ignition characteristics and the overall combustion process.

In summary, gasoline ignites through a combination of vaporization, mixture formation with air, reaching the ignition temperature, and exposure to an ignition source. The low flash point and ignition temperature of gasoline make it a highly effective fuel for engines, but also a substance that requires careful handling due to its flammability.

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"The most commonly known flammable liquid is gasoline. It has a flash point of about -50-- F (-65-- C). The ignition temperature is about 495-- F (232(232-- C) [sic], a comparatively low figure."read more >>