Question

For the reaction, \[ C_3H_8(g) + 5O_2(g) \rightarrow 3CO_2(g) + 4H_2O(l) \] at constant temperature, \( \Delta H = \Delta E \) is:

• A. RT
• B. \( -3RT \)
• C. 3RT
• D. \( -RT \)

Hint:

For reactions involving gases, \( \Delta H \) and \( \Delta E \) are related by \( \Delta H = \Delta E + \Delta n_g RT \).

Answer 1

The Correct Option is B

Step 1: Understand the relation between \( \Delta H \) and \( \Delta E \).
For reactions involving gases, the change in internal energy \( \Delta E \) is related to \( \Delta H \) by the relation: \[ \Delta H = \Delta E + \Delta n_g RT \] where \( \Delta n_g \) is the change in the number of moles of gases.
Step 2: Conclusion.
Thus, \( \Delta H = \Delta E \) when \( \Delta n_g = 0 \), and for this reaction, it results in \( -3RT \).
Final Answer: \[ \boxed{-3RT} \]