Thermodynamics
Practice Question Answer Set 1

Q.1. Give an example of a spontaneous process which is endothermic.

N2(g) + O2(g) → 2NO(g)

It is endothermic as well as spontaneous.

Answer

 

Q.2. State the second law of thermodynamics.

Whenever a spontaneous process takes place, it is always accompanied by an increase in total entropy of the universe.

∆Suniv = ∆Ssys + ∆Ssurr > 0

Answer

 

Q.3. State two ways by which the internal energy of a system may be changed.

(i) If the work is done by or on the system.

(ii) Heat is absorbed by the system or heat is evolved from the system.

Answer

 

Q.4. Give one point of difference : Extensive and intensive properties.

Extensive properties: Properties that depend on the quantity of matter contained in the system, e.g., mass, volume, etc.

Intensive properties: Properties which depend on the nature of the substance and not on the amount of substance, e.g., viscosity, etc.

Answer

 

Q.5. What will be the sign of ΔS for the following reaction?

CaCO3(s) → CaO(s) + CO2(g)

The sign of ∆S for the reaction,

CaCO3(s) → CaO(s) + CO2(g)

is +ve as the solid changes into gaseous state

Answer

 

Q.6. State the difference between adiabatic and isothermal processes.

In adiabatic process no heat can flow from the system to the surroundings or vice versa, whereas, in isothermal process temperature remains constant throughout the process.

Answer

 

Q.7. State first law of thermodynamics.

According to first law of thermodynamics, energy can neither be created nor be destroyed although it may be changed from one form to another.

Answer

 

Q.8. Define enthalpy of formation.

The enthalpy change accompanying the formation of one mole of a compound from its elements is called enthalpy of formation.

Answer

 

Q.9. When is bond energy equal to bond dissociation energy?

When bond energy is measured in isolated gaseous state, it becomes equal to bond dissociation energy.

Answer

 

Q.10. Under what conditions will a reaction be spontaneous if both ∆H and ∆S are negative?

∆G = ∆H – T.∆S

Given, ∆H = –ve and ∆S = –ve

For a reaction to be spontaneous, ∆G should be negative, reaction takes place spontaneously only at lower temperature.

Answer

Shopping Cart