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Part c) is incorrect. The correct answer is -233KJ as @jedigeis said!
I apologize.

No need to apologize! You did well, but the some other Steemians were faster this time! :)

Chemistry is not my strong, I prefer mechanics, but I like very much thermodynamics , it's ironic, right?
Thanks for this challenge @jaki01, it was very interesting.

Really nice to hear that you liked it ...