Combustibility refers to the ease with which a substance ignites and burns. This is largely determined by its:
* Flash Point: The lowest temperature at which a substance gives off enough vapor to ignite.
* Ignition Temperature: The minimum temperature required to initiate combustion without an external source of ignition.
Reactivity describes how readily a substance undergoes chemical change, especially in relation to other substances. This can involve:
* Oxidation: Reaction with oxygen, which can release heat and be explosive.
* Redox Reactions: Reactions involving the transfer of electrons.
* Decomposition: Breaking down into simpler substances.
Here's the connection:
* Many highly combustible substances are reactive: They readily react with oxygen, often in a rapid and exothermic way, causing combustion. This is why flammable liquids like gasoline are highly reactive with oxygen.
* Not all reactive substances are highly combustible: Some substances can react readily without involving fire. For example, sodium reacts vigorously with water, producing heat and hydrogen gas, but this reaction isn't considered combustion.
Examples:
* Highly Combustible and Reactive: Diethyl ether, gasoline, methane
* Highly Combustible, but not necessarily highly reactive: Wood, paper (combustion is a complex reaction with oxygen, but not necessarily a "reactive" substance in the chemical sense)
* Reactive, but not highly combustible: Sodium metal (reacts violently with water, but doesn't burn)
In summary:
Combustibility and reactivity are related concepts but not synonymous. While many combustible substances are reactive, not all reactive substances are combustible.
