Question

Which of the following are state functions?: Temperature, Enthalpy, Exergy, Internal Energy, Adiabatic Work, Heat (2 marks) b) Provide definitions for the following terms: i) Reversible process ii Ethalpy iii Entropy iv) Internal energy v) Isentropic process v) Adiabatic

Answer 1

Answer:

a) The state functions are: internal energy, temperature, enthalpy and exergy.

b) Definitions of terms are found in the explanation section.

Explanation:

a) The state functions are those quantities that are used to explain the state of a thermodynamic system.

b) reversible process: a reversible process returns the system to its original state without there being a variation in either the system or the external environment.

enthalpy: heat found in a system.

entropy: is the measure of disorder in a system

internal energy: internal energy is the energy that a molecule or atom possesses in a compound.

isentropic process: in thermodynamics is when there is no change in entropy.

adiabatic: when there is no heat change between the system and the surroundings.

Answer 2

Answer:

State functions are Temperature, Enthalpy, Energy, Internal Energy and Adiabatic work.

Explanation:

a) State functions are those thermodynamic functions which depends only on the final and initial state of the system but not on the path followed.

From the given options only heat is not a state function.

b)  (i) Reversible Process is the process which can be reversed at any point by making even very small changes in the properties of the system.

(ii) Enthalpy is defined as the total heat content of the system. It can also be written as the sum of internal energy and product of pressure and volume of the system.

(iii) Entropy defines the extent of randomness in any system.

So,  a substance in gaseous state has more entropy than its liquid state as gaseous particles can more freely.

(iv) Internal Energy is the energy that involves both potential and kinetic energy of the system. It involves energy for all sorts of random motions of the particles.

(v) Isentropic processes are processes in which entropy remains constant or entropy change is zero during the process.

(vi) Adiabatic processes are those process in which there is no heat change in the process. For example in thermos flask, there is no exchange of heat between system and surroundings.