Chapter 8.3, Problem 1RQ

Interpretation Introduction

Interpretation :

The four driving force for a chemical reaction must be explained.

Concept Introduction :

A chemical reaction is a chemical change in which new substance are generated with new appearance and properties.

Answer to Problem 1RQ

Four driving forces for a chemical reaction are given below.

• Formation of precipitate from two clear solutions
• Formation of water which can be removed to shift the equilibrium towards product side
• Transfer of electrons to gain more stability
• Formation of gas which can escape from the system and drives the reaction more towards product side.

Explanation of Solution

In the precipitation reaction concentration of the ions producing the precipitate decrease which drags the reaction more towards the product side to maintain the same equilibrium constant value.

  ${\text{NaCl(aq)+AgNO}}_{\text{3}}\text{(aq)}\to \text{AgCl(s)}\downarrow {\text{+NaNO}}_{\text{3}}\text{(aq)}\text{.}$

Here formation of AgCl(s) drives the reaction to product side.

In esterification reaction water is removed by acid catalyst to drive the reaction towards product side.

  ${\text{CH}}_{\text{3}}{\text{COOH(l)+CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{OH(l)}\to {\text{CH}}_{\text{3}}{\text{COOCH}}_{\text{2}}{\text{CH}}_{\text{3}}{\text{(l)+H}}_{\text{2}}\text{O(l)}\text{.}$

Few drops of concentrated sulfuric acid is used to take care of the water formed in this reaction.

  ${\text{Zn(s)+Cu}}^{\text{2+}}\text{(aq)}\to {\text{Cu(s)+Zn}}^{\text{2+}}\text{(aq)}\text{.}$

Zn being more electropositive it has a tendency to transfer electrons to Cu²⁺.

  ${\text{C(s)+O}}_{\text{2}}\text{(g)}\to {\text{CO}}_{\text{2}}\text{(g)}\text{.}$

In this reaction C is converted to CO₂ which escapes from the system and drags the reaction towards product side.