Thermodynamics Flashcards
State and Explain three types of system.
Open system:- Both exchange of mass and heat tales place
Closed system :- No exchange of mass, only heat exchange
Isolated system :- No heat or mass exchange
What is universe?
Surrounding + System is universe.
What are intensive properties of thermodynamics?
Properties which doesn’t depends upon the quantity or size of matter present.
Eg:- surface tension and temperature
What are extensive properties of thermodynamics?
Properties which depends upon physical body features like quantity and size.
Eg :- heat capacity and enthalpy
What are two types of functions?
State function and Path Function.
What is state function?
The property which depends on the state of a system and independent of a path followed to attain it, is called state function.
Eg :- Pressure and Volume
What is path function?
Property which depends upon the path is called path function.
Eg:- heat(Q) and work(W)
What are different types of thermodynamic processes?
1) Isothermal process
2) Isobaric Process
3) Isochoric Process
4) Adiabatic process
Explain Isothermal process.
Isothermal process has
Constant = T(temperature)
No change in temperature
Explain Isobaric Process
Isobaric Process has
Constant = P (pressure)
Change in pressure= 0
Explain Isochoric Process.
Isochoric Process has
Constant = Volume (V)
Change in v = 0
Explain Adiabatic Process.
In adiabatic process
There is no exchange of heat between system and surrounded
Q(heat) = zero
Importance of zeroth law of equilibrium
Zeroth law established temperature as indicator of thermal equilibrium
State first law of thermodynamics
First Law of Thermodynamics
Energy can neither be created nor destroyed although it can be
converted from one form to the other.
Mathematically, ∆ = + U q W
where, ∆ = U internal energy change
q = heat added to system
W = work added to system
State the sign convention for first law of thermodynamics
Sign convention
(i) q is + ve = heat is supplied to the system
(ii) q is – ve = heat is lost by the system
(iii) W is +ve = work done on the system
(iv) W is –ve = work done by the system
What is irreversible process
The process which cannot be reversed
and amount of energy increases. All natural processes are
irreversible.
What is internal energy
It is the total energy within the substance. It is the sum of many types
of energies like vibrational energy, translational energy, etc. It is an
extensive property and state function.
Its absolute value cannot be determined but experimentally change in
internal energy ( ) ∆U can be determined by
∆ = − U U U 2 1 or Σ − Σ U U P R
For exothermic process, ∆ = − U ve, whereas for endothermic process
∆ = U +ve.
U depends on temperature, pressure, volume and quantity of matter
and is independent of the method by which state has been attained.
State the zeroth law of thermodynamics
The law states that if the two systems are in thermal equilibrium with
a third system then they are also in thermal equilibrium with each
other. Temperature is used here to know whether the system is in
thermal equilibrium or not.
State Hess’s law
Overall the enthalpy change for a reaction is equal to sum of enthalpy change of individual steps in the reaction
What is spontaneous process
The process which has a natural tendency to occur and do not require any external influence for their occurance are spontaneous process
Features of spontaneous process
1) it occurs on its own and does not require any external agency to occur.
2) it proceeds in one direction and cannot take place in the opposite direction unless the external stimulant is present.
3) the spontaneous processes can be rapid or slow or spontaneity is not concerned with rate of the reaction
4) the spontaneous process continues till equilibrium reached. It is a natural process that tend to move in direction that leads to equilibrium.
What is entropy? Give it’s unit
Entropy is a measure of molecular disorder or randomness.
The entropy change of a system is equal to the amount of heat transferred to it in a reversible manner divided by the temperature in kelvin at which the transfer takes place. Thus,
∆S = Qrev/ T