Question

Calculate the entropy change ($in{\text{J K}}^{-1}$) when $132\text{g}$ of carbon dioxide expands reversibly and isothermally from an initial volume of $1\text{L}$ to $100\text{L}$ at $600K$ assuming ideal behaviour.

• A. $114.8{\text{J K}}^{-1}$
• B. $11.4{\text{J K}}^{-1}$
• C. $-114.8{\text{J K}}^{-1}$
• D. $-11.4{\text{J K}}^{-1}$

Answer 1

The correct option is A $114.8{\text{J K}}^{-1}$

The change in entropy for the isothermal reversible process is given as:
$△S=2.303nRlog\frac{V_2}{V_1}$
where $V_2$ is the final volume and $V_1$ is the initial volume.
$V_2=100L$
$V_1=1L$
Molar mass of $C{O}_2=44{\text{g mol}}^{-1}$
So, moles of gas, $n=\frac{132}{44}=3$
Putting all the values we get :
$△S=2.303\times 3\times 8.314\times log\frac{100}{1}=114.8{\text{J K}}^{-1}$