Question

For which of the following will the entropy of the system increase?

Answer 1

Answer :  The correct option is, (d) sublimation of dry ice.

Explanation :

Entropy : It is defined as the measurement of randomness or disorderedness in a system.

The order of entropy will be,

As we are moving from solid state to liquid state to gaseous state, the entropy will be increases due to the increase in the disorderedness.

As we are moving from gaseous state to liquid state to solid state, the entropy will be decreases due to the decrease in the disorderedness.

(a) Condensation of steam.

Condensation : It is a type of process in which the phase changes from gaseous state to liquid state at constant temperature.

In this process, phase changes from gaseous state to liquid state that means the degree of disorderedness decreases. So, the entropy will also decreases.

(b) Reaction of magnesium with oxygen to form magnesium oxide.

$Mg(s)+O_2(g)\rightarrow MgO(s)$

In this reaction, the randomness of reactant molecules are more (solid+gas) and as we move towards the formation of product the randomness become less (solid) that means the degree of disorderedness decreases. So, the entropy will also decreases.

(d) Reaction of nitrogen and hydrogen to form ammonia.

$N_2(g)+H_2(g)\rightarrow NH_3(g)$

In this reaction, the randomness of reactant molecules are more (2 moles of gas) and as we move towards the formation of product the randomness become less (1 mole of gas) that means the degree of disorderedness decreases. So, the entropy will also decreases.

(d) Sublimation of dry ice.

Sublimation : It is a type of process in which the phase changes from solid state to gaseous state without passing through the liquid state at constant temperature.

In this process, phase changes from solid state to gaseous state that means the degree of disorderedness increases. So, the entropy will also increases.