State the first law of thermodynamics. Explain its mathematical notation.

Explanation

Energy can neither be created nor be destroyed but energy in a process may be converted from one form to another form.
First law of thermodynamics is also known as law of conservation of energy.
Mathematically first law of thermodynamics can be represented as
`Q=DeltaE+W`
where
Q = Amount of heat absorbed by the system
`DeltaE` = Increase in internal energy of the system
W = Work done on a system
For infinitesimally small changes
`q=dE+W`
According to first law of thermodynamics a part of the around of heat (Q) absorbed by the system is used for increasing the internal energy `(DeltaE)` of the system and the remaining paert is used for doing work (W).
Heat absorbed by the system is given +sign, heat given out by the system is given -sign.
Work done by a system is given - sign and work done on a system is given + sign.