4C.3 Change in Enthalpy

[alicechien_4F]

For question 4C.3, it asks "Calculate the final temperature and the change in enthalpy when 765 J of energy is transferred as heat to 0.820 mol Kr(g) at 298 K and 1.00 atm (a) at constant pressure; (b) at constant vol- ume. Treat the gas as ideal."

I understand how to calculate the final temperature (using qp = nCp*deltaT), but how do you calculate the change in enthalpy? Thank you!

[Daniel Honeychurch1C]

When pressure is constant, q(p) = change in enthalpy. Therefore, the change in enthalpy = 765 J.

[Angela Prince 1J]

For question 4C.3, it asks "Calculate the final temperature and the change in enthalpy when 765 J of energy is transferred as heat to 0.820 mol Kr(g) at 298 K and 1.00 atm (a) at constant pressure; (b) at constant vol- ume. Treat the gas as ideal."

I understand how to calculate the final temperature (using qp = nCp*deltaT), but how do you calculate the change in enthalpy? Thank you!

How would you set up the equation when applying it to b) constant volume?

[JasonLiu_2J]

To find the change in enthalpy at constant volume, you would need to use the equation ∆ H = ∆ U +nR∆T. ∆U = q+w but since we know that volume is constant, we know that the work done will be zero (since w=-P∆V). Thus, ∆U=q. You would then plug in the given values of q, n, and R as well as your calculated value of T into the equation to find ∆H. Hope this helps!

[Joey_Okumura_1E]

The answer for 4C.3a is missing from the solution. Did you get the following answers:

4C.3a ΔH = 765 J, T_f = 343 K

[AHUNT_1A]

Using this for reference.

[Lakshmi Davuluri 1E]

The answer for 4C.3a is missing from the solution. Did you get the following answers:

4C.3a ΔH = 765 J, T_f = 343 K

Yeah, I also got that for part (a)