In this post, let’s look at bases and alkalis as tested in O Level Chemistry.
- What are bases
- bases and alkalis
- common properties of alkalis
- reactions of alkalis
- more on acids, bases and salts
What are bases?
Bases are metallic oxides or hydroxides that react with acids to form salt and water only.
Bases and alkalis
Alkalis are a subset of bases. Only bases that are soluble in water are called alkalis.
Since bases react with acids to form salt and water, so do alkalis. Like how we define acids in terms of Arrhenius acids, we can also do so for alkalis. Arrhenius bases are substances that dissociates in water to give hydroxide ions (OH–).
Common properties of alkalis
Alkalis are bitter in taste, have a soapy feel, are corrosive and turns red litmus paper blue.
Reactions of alkalis
1. Alkalis (and also bases) react with acids to form salt and water only This reaction is called neutralisation.
Word equation: acid + alkali –> salt + water
2. Alkalis react with ammonium salt to form salt, water and ammonia gas upon heating.
Word equation: alkali + ammonium salt –> ammonia gas + water + salt