Question

consider a mixture of air and gasoline vapor in a piston. original V is 30cm^3. if the combustion of misture releases 985J energy, to what volume will the gases expand against a constant pressure of 655 torr if all energy of combustion is converted into work ro push back the piston?

in L

Answer 1

Mel--This answer doesn't look right to me so check it out.
work = -p(V2-V2)= -985
change p to atmospheres.
change V to liters.
I get something like 1,000 liters and that sounds far to large. Perhaps Bob Pursley will look at this.

Answer 2

That should be -P(V2-V1) and solve for V2.
Also, last sentence should read "far too large."

Answer 3

type this in the Google search window:

985joules/655torr in liters

That gives you delta Volume.

Answer 4

I found my problem. I didn't convert J to L-atm.
985 J/101.325 = 9.72
Then -9.72 = -(655/760)(V2-V1)
9.72 = 0.862V2 - 0.862*0.03
V2 = 11.3 liters.