# Worksheet on Chemical equilibrium

Chemical equilibrium is used to describe the condition on which the concentration of the product  and reactant doesn’t change according to time. This condition takes place only on reversible reaction.

This concept was developed after Berthollet (1803).

Here, you can test your knowledge about chemical equilibrium just by solving the questions written below.  Answers to the following question are given on the button of the page.

Questions:

1. A reversible reaction is said to have attained equilibrium, when:

(a)    A backward reaction stops

(b)   Both backward and forward reactions take place at equal speed

(c)    Both backward and forward reactions stop

(d)   Concentration of each of the reactants and products becomes equal

2. The equilibrium between water and its vapour, in an 0pen—vessel:

(a)    Can be achieved

(b)   Depends upon pressure

(c)    Cannot be achieved

(d)   Depends upon temperature

3. Chemical equilibrium is dynamic in nature, because:

(a)    The equilibrium is maintained rapidly

(b)   The concentration of reactants and products is constant but different

(c)    The concentration of reactants and products becomes same at equilibrium

(d)   Both forward and backward reactions occur at all times with same speed ( )

4. A liquid is in equilibrium with its vapour at its boiling point. The molecules in these two phases will have equal:

(a)    Potential energy

(b)   Internal energy

(c)    Intermolecular

(d)   Kinetic energy

5. Just before attaining equilibrium by a reversible reaction, it is found that:

(a)    Velocity of forward reaction decreases but backward reaction increases

(b)   Velocity of both forward and backward reactions decreases

(c)    Velocity of both forward and backward reactions increases

(d)   Velocity of forward reaction increases but that of backward reaction decreases

6. A characteristic feature of reversible reactions is that they:

(a)    Proceed to completion

(b)    Never proceed to completion

(c)    Proceed to completion when the concentration of the reactants decreases

(d)   Proceed to completion when the concentration of the reactants increases

7. The reaction $PCl_5 (g) \leftrightharpoons PCl_3 (s) + Cl_2 (g)$ is an example of:

(a)    Backward

(b)   Forward

(c)    Irreversible

(d)   Reversible