What is the main limitation of the first law of thermodynamics?

Write mathematical statement of first law of thermodynamics.

In a process, 100J of heat energy is supplied and 50J of work is done on the system. What is the change in internal energy of the system ?

What is the difference between heat and work?

38. The enthalpies of all elements in their standard states are:

• unity

• zero

• <0

• different for each element

Define extensive property ? 

Why heat changes reported are usually enthalpy changes and not internal energy?