ok so DELTA U = Q - W Where U is internal energy, Q is heat transferred from or to the system and W is the work done BY the gas right? I always mix up U and Q, the concepts. My teacher said U depends entirely on temperature, is this right?? Also, if Q =ncDELTA T, isnt Q also dependent on a change of temperature? We saw that for an isotermic process, Q = W......WHY!?!?! If it is isotermic, isnt delta T = 0 , so that Q = is 0? Instead my teacher wrote that for an isotermic process, delta U is zero? Can someone explain this? Thanks a lot for reading and helping.