TD Flashcards
what is a thermodynamic syste
a certain quanitity of matter which can be influenced by heat and is enclosed in a boundary surface is called as thermodynamic system.
what are the 2 types of walls
i) diathermous/diathermic walls= conducting walls ( allows heat transfer)
(ii) adiabati walls- boundary that does not allow transfer of heat
what are the 3 types of system
open
closed
isolated
state 0th law of thermodyamics
Zeroth Law of
Thermodynamics, which states that ‘two
systems in thermal equilibrium with a third
system separately are in thermal equilibrium
with each other’
what is thermal equilibrium
2 bodies are said to be in thermal equilibrium when the thermodynamic variables like pressure, temperature, volume etc do not change with time
what is internal energy
intenral energy is the total energy possessed by a body vy virtue of its molecular motion and molecular configuration, ie it is the sum of potential and kinetic energy.
what is heat and work
Heat and work are two distinct modes of
energy transfer to a system that results in
change in its internal energy. (a) Heat is
energy transfer due to temperature
difference between the system and the
surroundings. (b) Work is energy transfer
brought about by means (e.g. moving the
piston by raising or lowering some weight
connected to it) that do not involve such a
temperature difference.
what is the first law of td
the energy (∆Q) supplied to the system goes
in partly to increase the internal energy of the
system (∆U) and the rest in work on the
environment (∆W). Equation (11.1) is known as
the First Law of Thermodynamics.
what are thermdynamic processes
A process in which the temperature of the
system is kept fixed throughout is called an
isothermal process. The expansion of a gas in
a metallic cylinder placed in a large reservoir of
fixed temperature is an example of an isothermal
process. (Heat transferred from the reservoir to
the system does not materially affect the
temperature of the reservoir, because of its very
large heat capacity.) In isobaric processes the
pressure is constant while in isochoric
processes the volume is constant. Finally, if the
system is insulated from the surroundings and
no heat flows between the system and the
surroundings, the process is adiabatic.
differentiate adiabatic and isothermal processes
i) Adiabatic process:
Temperature is variable. There is no heat transfer between the system and surrounding.
- Walls of the system are adiabatic
- Rapid process
- Chanegin internal energy is not 0. It is equal to the work done on the system.
- PV^ gammma=const
ii) Isothermla process:
Temperatue is constant. There is heat transfer between system and surroundings
- Slow process
- Walls are diathermic
- change in ineternal energy is 0. work done by system is equal to the heat absorbed by the system
- PV= const
what are the drawbacks of 1st law of td
- failed to explain the direction of heat flow
- failed to explain the change in state the system undergoes
what is kelvin planck statement of 2nd law of td
No process is possible whose sole result is the
absorption of heat from a reservoir and the
complete conversion of the heat into work.
what is clausius stamenet of 2nd law of td
No process is possible whose sole result is the
transfer of heat from a colder object to a
hotter object.
What are the conditions for isothermal process
There should be free exchange of heat between the system and its surroundings. All walls of the container and the piston must be perfectly conducting.
(i) The system should be compressed or allowed to expand very slowly so that there is a sufficient time for the exchange of heat between the system and its surroundings.
Since these two conditions are not fully realised in practice, therefore, no process is perfectly isothermal.
What are the 2 conditions for adiabatic process
There should not be any exchange of heat between the system and its surroundings. All walls of the container and the piston must be perfectly insulating.
(ii) The system should be compressed or allowed to expand suddenly so that there is no time for the exchange of heat between the system and its surroundings.
Since, these two conditions are not fully realised in practice, so no process is perfectly adiabatic
