Chapter 7, Problem 4A

Interpretation Introduction

Interpretation:

The evidence should be determined for the given change which represents a chemical reaction.

Concept Introduction:

The reaction in which one or more species that are reactants reacts with each other to form one or more other species that are products, it is known as a chemical reaction. In a chemical reaction, the chemical transformation of one or more chemical substances to other chemical substances takes place. This also involves the formation of the breaking of chemical bonds during the reaction.

Answer to Problem 4A

The given change represents a chemical reaction. The presence of acetic acid is confirmed by its pungent smell when the aspirin bottle is left open to the air.

Explanation of Solution

The chemical formula of aspirin is ${\text{C}}_{\text{9}}{\text{H}}_{\text{8}}{\text{O}}_{\text{4}}$ . It is a chemical compound and also known as acetylsalicylic acid.

When aspirin is exposed to air, the humidity present in the air, that is, water reacts with aspirin to form salicylic acid ${\text{C}}_7{\text{H}}_6{\text{O}}_3$ and acetic acid ${\text{C}}_2{\text{H}}_4{\text{O}}_2$ .

Vinegar consists of water and acetic acid. Thus, when a bottle of aspirin is left open to the air, the presence of acetic acid is confirmed by its pungent smell. This change denotes a chemical reaction.

The chemical reaction is written as:

  ${\text{C}}_{\text{9}}{\text{H}}_{\text{8}}{\text{O}}_{\text{4}}+{\text{H}}_{\text{2}}\text{O}(\text{humidity in air})\to {\mathrm{C}}_7{\mathrm{H}}_6{\mathrm{O}}_3+{\mathrm{C}}_2{\mathrm{H}}_4{\mathrm{O}}_2$