Question

How can I write the formula of calcium oxide?

Answer 1

Hint: The calcium oxide is an ionic compound formed by calcium cation and oxide anion. The calcium contains positive charge with +2 oxidation state and oxide contains negative charge with -2 oxidation state.

Complete step by step answer:
The calcium oxide is a chemical compound which is alkaline in nature. The calcium oxide is formed from a calcium atom and an oxygen atom. The chemical formula or the molecular formula of the calcium oxide is written as CaO. The calcium oxide is known as quicklime and it is one of the oldest chemical compounds.
The molecule of calcium oxide CaO contains a calcium cation and oxide anion. The calcium ion is in +2 oxidation state and the oxide ion is in -2 oxidation state. The ionic form of calcium oxide is given as $C{a}^{2+}{O}^{2-}$.
The calcium oxide is prepared from the thermal decomposition of limestone which contains calcium carbonate.
The reaction for the preparation of calcium oxide is shown below.
$CaC{O}_3\to CaO+C{O}_2$
In this reaction, calcium carbonate undergoes thermal decomposition to form calcium oxide and carbon dioxide.
When water is added in calcium oxide CaO (quick lime), calcium hydroxide $Ca(OH{)}_2$ is formed. The calcium hydroxide is known as lime water. The calcium hydroxide is also known as slaked lime.
The reaction for the preparation of calcium hydroxide is shown below.
$CaO+H_{2}O\to Ca(OH{)}_2$
In this reaction, calcium oxide reacts with water to form calcium hydroxide.

Note:
The carbon dioxide formed in the production of calcium oxide is removed so that the reaction can proceed until the process is complete according to Le-Chatelier’s principle. The calcium oxide is also referred to as burnt lime.