Question

The first law of thermodynamics is a special case of:
1. Newton's law
2. the law of conservation of energy
3. Charles' law
4. the law of heat exchange

Answer 1

Correct Answer - Option 2 : the law of conservation of energy

CONCEPT:

The first law of thermodynamics:

• The first law of thermodynamics states that the change in internal energy of a system is equal to the sum of the heat exchanged with the surrounding and the amount of work done by the surrounding on the system. 

⇒ ΔU = q + W

Where U = internal energy of the system, q = amount of heat, and W = work done 

EXPLANATION:

The statement for the first law of thermodynamics can also be interpreted as:

• Any change in the internal energy of the system must result in a corresponding change in the energy of the surrounding. 
• Energy can neither be created nor be destroyed, it can only be changed from one form to another. 
• Hence, option 2 is correct.

• The second law of thermodynamics: The total entropy of the universe (system + surrounding) must increase in a spontaneous process.

ΔStot > 0

• The third law of thermodynamics: The entropy of a perfectly crystalline solid at absolute zero temperature (T = 0 K) is zero.

S(T = 0 K) = 0