Chemical Thermodynamics Question 365
Question: For the combustion reaction at $ 298K $
$ 2Ag( s )+1/2O_2( g )\xrightarrow{{}}2Ag_2O( s ) $ Which of the following alternatives is correct-
Options:
A) $ \Delta H=\Delta U $
B) $ \Delta H>\Delta U $
C) $ \Delta H<\Delta U $
D) $ \Delta H $ and $ \Delta U $ has no relation with each other
Show Answer
Answer:
Correct Answer: C
Solution:
- $ \Delta H=\Delta U+\Delta nRT $
$ \Delta n=n_{p}-n_{R} $ Now, $ \Delta n=2-\frac{5}{2}=-\frac{1}{2} $
$ \therefore \Delta H=\Delta U-\frac{1}{2}RT $ Thus, $ \Delta U=\Delta H+\frac{1}{2}RT $
$ \therefore \Delta U>\Delta H $
