For the combustion of propane gas, , carried out at a constant temperature, what is the value of ? — Thermodynamics and Thermochemistry Chemistry Question
Question
For the combustion of propane gas, $C_3H_8(g) + 5O_2(g) \rightarrow 3CO_2(g) + 4H_2O(l)$, carried out at a constant temperature, what is the value of $\Delta H - \Delta U$?
Answer: B
💡 Solution & Explanation
The fundamental relationship is $\Delta H = \Delta U + \Delta n_g RT$. We only count gaseous moles for $\Delta n_g$. $\Delta n_g = (\text{moles of gaseous products}) - (\text{moles of gaseous reactants}) = 3 - (1 + 5) = -3$. Therefore, $\Delta H - \Delta U = -3RT$.
💬Ask on WhatsApp →
Still have doubts about this question?
Send it to our AI chemistry tutor on WhatsApp — gets answered in minutes