4D.5

[emmaferry2D]

For a certain reaction at constant pressure, ΔH
15kJ, and 22 kJ of expansion work is done on the system by compressing it into a smaller volume.What is ΔU for this process?

How would you do a problem like this?

I thought you would use the equation delta H= deltaU+PdeltaV but I am a little stuck on what to plug in to this equation

[Eliana Witham 2H]

We know that deltaU = q + w, and the question actually gives you the values for q and w. For a constant pressure, deltaH = q. Also, work is done on the system, meaning that your given work value is positive. You can add these numbers for the answer.

[Alan Huang 1E]

Using ΔU = q + w:

We find that ΔU = ΔH + w

Just plug in values of ΔH = -15 and w = 22 we get

ΔU = -15 + 22
ΔU = +7 kJ