First law and Thermodynamics Processes

Thermodynamic System

part of the universe in which observation & the environment

Boundary

the wall that separates the system & environment

Surroundings

it contains everything other than the system. It is the outside of the system after all.

System & Surrounding

together, they make up the universe

Work

the force used to transfer energy between a system & it's surroundings and is needed to create heat & transfer thermal energy

Heat

is the overall energy of all molecular motion on the object. It is the transfer of thermal energy

Internal Energy

is the sum of all kinds of energies the particles that form the system

Kinetic energy

the energy of an object possessed when in motion

Potential energy

stored energy in any object. It is also known as the "energy at rest"

First law of thermodynamics

states that energy can be converted from one form to another with the interaction of heat, work & internal energy, but it cannot be destroyed or created under any circumstances

Formula of the first law of Thermodynamics

∆U = q + W

∆U

is the total change of the internal energy of the system

q

is the heat exchange between system & surroundings

W

the work done by or on the system

Endothermic Reactions

a kind of reaction where the system absorbs energy from its surroundings in the form of heat

Exothermic Reaction

is the opposite of Endothermic. It releases energy by light or heat to surroundings

If the system releases heat…

then its internal energy will increase decrease and vice versa

If work is done ON the system…

then its internal energy would also increase and vice versa

The energy lost by the system is…

equal to the energy absorbed by its surroundings and vice versa

Thermodynamics Processes

Isochoric, Isobaric, Isothermal, Adiabatic, Cyclic, Reverse and Irreversible Process

Isochoric process (constant volume)

a Thermodynamic Processes that takes place at constant volume so that no work is done ON or BY the system

Example of Isochoric

boiling water in a tightly sealed undeformable container

Isobaric Process (constant pressure)

a type of Thermodynamic Processes in which there is a change in internal energy, work done BY the system, heat flowing into the system, while pressure remains constant

Example of Isobaric

boiling water in an open lid pot at atmospheric pressure

Isothermal Process (constant temperature)

a process during which the systems temperature remains constant while pressure & volume changes

Isothermal Process example

Phase changes of water from solid to liquid and gas through melting and Vaporisation

Adiabatic Process (no heat transfer)

a Thermodynamic process insulated from its environment so that the state of changes and heat is not able to enter or leave the system. There's only the work happening on the system

Example of Adiabatic Process

A functioning piston

Adiabatic expansion

it leads to lowering of temperature by expanding the gas molecules

Adiabatic compassion

it leads to the increase of the temperature of gas molecules due to compression

Cyclic Process

a Thermodynamic process wherein the state of the system at the end is the same state at the beginning

Reversible process

is an ideal Thermodynamic process that once having taken place, can be reversed & in doing so leaves no change in either system or surroundings.

Cyclic Process example

the cycle of rain

Irreversible Process

a Thermodynamic process in which the system & surroundings do not return to their original condition once the process is initiated

Example of Irreversible Process

an automobile that burns fuel to move. Those fuels cannot be reversed again

Causes of irreversibility

Friction, unrestrained expansion, heat transfer through a finite temperature difference, mixing of different substances, chemical reactions, inelastic deformation, electric resistance