FSc Notes Chemistry Part 1 Chapter 8 Chemical Equilibrium Lecture 1

FSc Notes Chemistry Part 1 Chapter 8 Chemical Equilibrium Lecture 1

Chemical Equilibrium

Reversible Chemical Reaction:

Any chemical reaction in which the reactants are converted into the products and the products are converted back into the reactants, is known as reversible chemical reaction.

For example when hydrogen gas reacts with iodine hydrochloric acid (HI ) is formed but HI immediately converts back into H2 and I2, so it is a reversible reaction , i.e
H2(g) + I2(g) 2HI(g)

In case of representing a reversible chemical reaction by means of a chemical equation, the reactants and products are separated by means two opposite half arrows (i.e. ) From the above discussion, it is clear that during a reversible chemical reaction, actually two reaction occurring. One is to the right side, converting the  reactants into the products and is known as “forward reaction”

e.g

H2 + I2 ------------------ 2HI

The other is to the left side, converting the products back into the reactants and is known as “reverse or backward reaction”

e.g

H2 + I2 ---------------------2HI

Rate of Reaction :

The change in concentration of reactants or products per unit time is called as rate of reaction.

During a chemical reaction, with the passage of time , the concentration of reactants decreases and the of the products increases.

So in terms of reactants, the rate may be defined as the decrease in concentration of reactants per unit time.

In case of reversible reactions there are two reactions i.e forward reaction and reversible reaction,

so we can discuss the rate of such reactions as :

Rate of forward reaction & Rate of reverse reaction.

Rate of Forward Reaction

The change in concentration of reactants during a reversible reaction, per unit time is known as rate of forward reaction.

Rate of Reverse Reaction.

The change in concentration of products, during a reversible reaction , reaction ,per unit time is known as rate of reverse reaction.

Written by: Asad Hussain