Chapter 5, Problem 5.39UKC

Use the molecular art to identify the process as a chemical reaction or a physical change. If a chemical reaction occurs, write the equation from the molecular art. If a physical change occurs, identify the phase change.

Interpretation Introduction

Interpretation:

The type of change (physical or chemical change) represented by the molecular art has to be given and explained.  If the process is physical, the phase change has to be written and if the process is chemical, the equation has to be written.

Concept Introduction:

Physical change:  An alteration of substance without changing its composition is called as physical change.  The change in state of a substance is the most common physical change.  Example:  Melting of an ice cube to form liquid water.

Chemical change:  The conversion of one material to another is called as chemical change (or) chemical reaction.  Example: formation of water from hydrogen and oxygen is a chemical reaction because there is difference in the composition of the material at the beginning and end of the process.

Explanation of Solution

The given representation is,

Figure 1

The above represent represents a chemical change because new products are formed by chemical bonds.

The three red spheres represent ozone $\left({\text{O}}_{\text{3}}\right).$

The combination of red and black spheres represents carbon monoxide $\left(\text{CO}\right)\text{.}$

The combination of two red spheres with one black sphere represents carbon dioxide $\left({\text{CO}}_{\text{2}}\right)\text{.}$

The two red spheres represent oxygen $\left({\text{O}}_{\text{2}}\right)\text{.}$

The chemical equation is,

  $\text{2}\text{CO+2}{\text{O}}_{\text{3}}\stackrel{}{\to }\text{2}{\text{CO}}_{\text{2}}\text{+2}{\text{O}}_{\text{2}}$

The reaction is not balanced.

The balanced equation is,

  $\text{CO+}{\text{O}}_{\text{3}}\stackrel{}{\to }{\text{CO}}_{\text{2}}\text{+}{\text{O}}_{\text{2}}$