Question

A system performs 354 J of work on its surroundings while losing 133 J of internal energy. How would you determine the heat transferred to the system during this process?

Answer 1

I found `Q=221J`

Explanation:

We could use the First Law of Thermodynamics:
`DeltaE_("int")=Q-W`
where the variation of internal energy `DeltaE_("int")` is equal to the difference between heat `Q` and work `W`.
I use the convention that:

heat in Positive
heat out Negative
work in Negative
work out Positive

In our case internal energy decreases so: `DeltaE_("int")<0`:
`-133=Q-(+354)`
so `Q=354-133=221J`