Thank you so much for this comprehensive reply - I see where my faulty thinking was. I incorrectly assumed the amount of heat (q) evolved would be the same under both conditions. It all makes sense now ;D
Greetings! I've been brushing up on some thermodynamics recently and came across a perplexing sentence in my notes and text from undergrad.
It says that for a combustion reaction, such as the combustion of heptane:
C7H16 (l) + 11O2 (g) ---> 7CO2 (g) + 8H2O (l)
That this process carried out at...