[scrum]

Calculate the energy required to heat 1.10 kg of ethane gas (C2H6) from 24.0°C to 79.0°C first under conditions of constant volume and then at a constant pressure of 2.00 atm. Calculate E, H, and w for these processes. (See Table 9.1 for relevant data.)

It wants q, DeltaE, DeltaH, w. For both a constant V and a Constant P, in kJ units.

I obtained both q values with no problem, and then realised that DeltaE would be the same in a system of constant volume, but then when it came time to calculate the DeltaE for a constant pressure I had a problem.

I know that

DeltaE = q + w

I also know that in for my problem DeltaE = (106)KJ + w

and I know

w = -pDeltaV

and for my problem w = -2atm DeltaV

That's where my formulas run dry. I don't know how to find Delta V in this case.

[Yggdrasil]

Ideal gas law.

[scrum]

Ideal gas law.

Thanks

I'm still having trouble with solving for work with constant P.

pv = nRT

DeltaV = nRT[1] / p  - nRT[2] / p

DeltaV = (36.58Mol)(.08206)(79K) / (2)Atm  - (36.58mol)(.08206)(24) / (2)atm

DeltaV = 85.6 L



Work = -P * DeltaV
W = -2atm * 85.6L
-171.2 atm L

-171.2 atm L  * 101.3 J / atm L = -17342 J

w = -17.3 Kj

Online homework says it's wrong.

[Yggdrasil]

You forgot to convert the temperature to Kelvins.