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Q.12 What do you understand by the Macroscopic & Microscopic approach of thermodynamics?

While macroscopic is concern with certain quantity of matter and its behaviour, microscopic approach deals with molecular and atomic behaviour of matter and energy.

Q.13 Define reversible process?

Reversible process is one in which both the system and the surroundings are returned to their original states, which is not so in the case of irreversible process. In actual practice, all processes are irreversible.

Q.14 Define Adiabatic process?

Adiabatic process is one in which there is no flow of heat between a system and its surroundings.

Q. 15 What do you understand from Exergy and Anergy?

Exergy (Available Energy) can be converted into work but Anergy (Unavailable Energy) can not be converted to work.

Q. 15 Explain Carnot Cycle?

The Carnot cycle is a theoretical ideal thermodynamic cycle proposed by French physicist Nicolas Léonard Sadi Carnot in 1824 and expanded upon by others over the next few decades.

The four stages in the Carnot cycle. (A) Stage 1: Isothermal expansion under heat input Q1, (B) Stage 2: Adiabatic expansion accompanied by a fall in temperature T1 to T2, (C) Stage 3: Isothermal compression, Q2 exhausted, (D) Stage 4: Adiabatic compression accompanied by an increase in temperature T2 to T1.

Q.16 Define Enthalpy?

When a process takes place at constant pressure, the heat absorbed or released is equal to the Enthalpy change. Enthalpy is sometimes known as “heat content”, but “enthalpy” is an interesting and unusual word, so most people like to use it. Etymologically, the word “entropy” is derived from the Greek, meaning “turning” and “enthalpy” is derived from the Greek meaning “warming”. As for pronunciation, Entropy is usually stressed on its first syllable, while enthalpy is usually stressed on the second.

Enthalpy(H) is the sum of the internal energy(U) and the product of pressure(P) and volume(V).

Enthalpy H can be written as,

H = U + pV

Where, H = Enthalpy of the system

U = Internal energy of the system

p = Pressure of the system

V = Volume of the system

Enthalpy is not measured directly, however, the change in enthalpy (ΔH) is measured, which is the heat added or lost by the system. It is entirely dependent on the state functions T, p and U.

Q.17 Define Heat?

Energy in transition flowing by virtue of temperature difference from one system to other when two are in contact called Heat.

Q.18 Define Specific Heat?

Specific heat is the heat required by 1 unit mass of substance to raise the temperature by one degree.

Q.19 Difference between first & second laws of thermodynamics.

The first law is concerned with quantity and sum total of energy but the second law accounts for the quality, availability, reversibility, losses, efficiency, etc. It explains the difference between heat and work, exergy and anergy.

Q. 20 Difference between Enthalpy and Entropy?

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