[briofuel88 (OP)]

In an Internal Combustion Engine, what is Chemically happening to Oxygen and

Gasoline [when the spark plug ignites] that makes them combust with heat??



THANKS!!

[acecharly]

the oxygen and gasoline are chemically reacting and rearranging there structures to produce new molecules, and a byproduct of this is a high release of energy.

[evan_au]

Gasoline = C₈H₁₈ (approximately - it's a mixture of many chemicals containing Carbon and Hydrogen in various ratios)
Oxygen = O₂
Gasoline + Oxygen = liquid sloshing in a petrol tank
Gasoline + Oxygen + spark = CO₂ + H₂O + Energy (more spark) = Explosion

The purpose of the electric spark is to disrupt some of the gasoline & oxygen molecules, which then recombine to form carbon dioxide & water, releasing energy which can be harnessed to drive your vehicle.

To ensure that it works well, you need:

• The right ratio of gasoline & oxygen
• With the gasoline completely vaporised and completely mixed with the oxygen
• At the right temperature and pressure
• With the spark applied at just the right time to ensure complete combustion
• All of these depend on the type of fuel that you use (gasoline for cars is a different hydrocarbon mixture than Diesel for trucks or Biofuel)
  

If you don't get it exactly right, you can get:

• Pollution: carbon soot, carbon monoxide, nitrous oxide
• Backfire: Uncombusted gas released into the exhaust pipe, where it explodes
• Poor fuel consumption
• An engine that overheats, or wears out too quickly
• An engine that may actually run backwards(!)
• An engine that doesn't start at all