Question

What is the composition of water? In what volume are its two constituent elements combined?

Answer 1

Hint: Think about the chemical formula of water and also the free molecular states of hydrogen and oxygen. Balance the reaction and find volume using the concept of moles.

Complete step by step answer:
Water is a compound that is extremely important for the survival of all living beings. The chemical formula of water is known to be ${{H}_{2}}O$. It contains two hydrogen atoms bonded to one oxygen atom. The oxygen atom is $s{{p}^{3}}$ hybridized; 2 of the degenerate orbitals are occupied by the lone pairs on oxygen and two are occupied by the bond pairs they form with the hydrogen atoms. This gives the molecule a bent shape if only the atomic nuclei are considered while mapping the shape.
Now, let us move on to how water is formed. We know that the molecules of the elements hydrogen and oxygen are present in diatomic pairs in nature. So, the chemical formula of hydrogen gas is ${{H}_{2}}$ and oxygen gas is ${{O}_{2}}$. The general, unbalanced reaction for the formation of water will be:
\[{{H}_{2}}+{{O}_{2}}\xrightarrow{energy}{{H}_{2}}O\]
Now, let us look at the balanced reaction:
\[2{{H}_{2}}+{{O}_{2}}\xrightarrow{energy}2{{H}_{2}}O\]

This reaction requires tremendous amounts of energy since the reactants are electrolyzed to form water and the gases hydrogen and oxygen are pretty stable in their molecular forms.
So, two moles of hydrogen gas is required to reduce one mole of oxygen gas. The concept of moles explains that one mole of any substance will have a constant volume. Thus, we can say that for this reaction to proceed and form water, the volume of hydrogen will be twice as that of the volume of oxygen.

Note: The volume of one mole of any substance is said to be 22.4L at standard temperature and pressure. Any anomalies in the expansion of real gases when the temperature or pressure has changed considerably will change the ratio of the volume of the gases required for the production of water.