Definition
A process in which two or more substances interact at the molecular level to form one or more different substances, with the new substances having different chemical properties from the originals. The process typically involves the breaking and forming of chemical bonds and is often accompanied by the release or absorption of energy in the form of heat, light, or pressure.
Plain English
When two or more substances meet and change into something different, with new properties. The change is often accompanied by heat, light, or a release of gas.
Context Anchor
Seen in aircraft systems, engine combustion, battery care, fire safety, corrosion, and hazardous materials discussions.
Derivation
From Latin 'reagere', meaning 'to act back'. A chemical reaction is literally substances 'acting back' on each other to produce something new.
Why Pilots Care
Pilots rely on controlled chemical reactions for engine power and must prevent unwanted ones that cause corrosion or battery failure.
Grounding Statement
When fuel burns, the fuel and oxygen do not simply disappear; they change into new gases and heat.
Intuition Check
Do not assume a chemical reaction has to look dramatic, like an explosion or bubbling liquid. A slow process such as corrosion is also a chemical reaction because the material is changing into something new.
Example Sentence 1
The chemical reaction between fuel and oxygen inside the cylinder produces the heat that drives the engine.
Example Sentence 2
Moisture on the wing skin starts a slow chemical reaction that can turn into visible corrosion if left unchecked.