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.

 

[PJC01]

The first formula, dQ=dU+dW, represents the first law of thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system plus the work done on the system. This formula is used to calculate the change in energy of a system when heat is added or work is done on the system.

The second formula, dU=dQ+dW, is not a valid formula as it violates the first law of thermodynamics. This formula suggests that the change in internal energy is equal to the sum of the heat and work, which is incorrect. The correct formula is dQ=dU+dW, where the heat and work are added together to calculate the change in internal energy.

In summary, the main difference between these two formulas is that the first one is a correct representation of the first law of thermodynamics, while the second one is not. The first formula is used to calculate the change in energy of a system, while the second one is not valid and should not be used.