Question

equation for first law of thermodynamics​

Answer 1

Since the First Law of Thermodynamics states that energy is not created nor destroyed we know that anything lost by the surroundings is gained by the system. ... Therefore, q and w are positive in the equation ΔU=q+w because the system gains heat and gets work done on itself.Jan 23, 2018

Answer 2

first law as ΔU=Q+W.

It is the same law, of course - the thermodynamic expression of the conservation of energy principle