Difference between the two following formulas

[Kibz665]

Can some one please tell me what is the difference between the two following formulas and when it is used:
dQ=dU+dW
dU=dQ+dW

 

[Jorriss]

Are you asking about the different conventions used by physicists and chemists for the 1st law..?

 

[Chestermiller]

Can some one please tell me what is the difference between the two following formulas and when it is used:
dQ=dU+dW
dU=dQ+dW

In the first equation, dW represents the work done by the system on the surroundings. In the second equation, dW represents the work done by the surroundings on the system. Both conventions are used, depending on the author.

 

[Kibz665]

Thanks that was very helpful.