Chapter 7.3, Problem 4RQ

Interpretation Introduction

Interpretation :

Symbols shown in red in the given chemical reaction must be explained.

Concept Introduction :

In chemical equation formula of compounds are given along with the physical states. Coefficients and subscripts can be found in chemical equation.

Answer to Problem 4RQ

‘2’ in 2O₂ represents that 2 moles of oxygen is reacting with 1 mol of methane (CH₄).

‘2’ in H₂O represents that there are 2 H atoms in the molecule of water (H₂O).

Explanation of Solution

Coefficients in chemical reaction give the idea of mole ratio in which the reaction is taking place. But the subscripts gives idea of how many particular type of atoms is there in a molecule.

  ${\text{CH}}_{\text{4}}{\text{(g)+2O}}_{\text{2}}\text{(g)}\to {\text{CO}}_{\text{2}}{\text{(g)+2H}}_{\text{2}}\text{O(g)}\text{.}$

In this reaction it is clear that per mole of methane 2 moles of oxygen is required for complete combustion. From the formula of water (H₂O) it is clear that there are 2 hydrogen atoms in one molecule of water which is represented by the subscript ‘2’ in H of H₂O.