Basic Anhydride
Definition and meaning of Basic Anhydride in chemistry.
A basic anhydride is an oxide that reacts with water to form a base (alkaline compound). Common basic anhydrides are oxides of active metals that produce hydroxides when combined with water.
In more detail
Basic anhydrides result from the removal of water from bases, representing their dehydrated form. When a basic anhydride accepts water molecules, it undergoes hydration to regenerate the original base, a process called rehydration. For example, sodium oxide (Na2O) is the basic anhydride of sodium hydroxide (NaOH). These compounds are typically oxides of alkaline and alkaline-earth metals in Groups 1 and 2 of the periodic table, making them important in industrial chemistry, construction, and materials science.
Key facts
| General Formula | Metal Oxide (MₓOᵧ) |
|---|---|
| Common Examples | Na2O, CaO, BaO, K2O |
| Product When Hydrated | Metal Hydroxide (base) |
| Field | Inorganic Chemistry |
Calcium oxide (CaO), commonly known as quicklime, is a classic basic anhydride that reacts vigorously with water to form calcium hydroxide: CaO + H2O → Ca(OH)2. This reaction is highly exothermic and releases significant heat, which is why quicklime must be handled carefully in laboratory and industrial settings.
Frequently asked questions
What's the difference between a basic anhydride and an acidic anhydride?
Basic anhydrides are oxides of metals that form bases (hydroxides) when hydrated (e.g., Na2O + H2O → 2 NaOH), while acidic anhydrides are oxides of nonmetals that form acids when hydrated (e.g., SO3 + H2O → H2SO4).
Why is calcium oxide called quicklime?
Calcium oxide reacts extremely quickly and vigorously with water in a highly exothermic reaction, releasing substantial heat, hence the name 'quicklime.'