Question

The unit of molar gas constant is :

• A. $J K^{-1} \,mol ^{-1}$
• B. $J$
• C. $JK$
• D. $ J \,mol^{-1}$

Answer 1

Answer: (A)

From ideal gas equation $P V=\mu R T$
$\Rightarrow R=\frac{P V}{\mu T}$
$\therefore $ Unit of $R=\frac{\text { Unit pressure } \times \text { unit of volume }}{\text { mol } \times \text { unit of temperature }}$
$=\frac{\text { newton-metre }^{-2} \times \text { metre }^{3}}{\text { mol }-K}$
$=\frac{\text { newton-metre }}{\text { mol-K }}$
$=\frac{\text { joule }}{\text { mol-K }}$
$=\left(J-mol^{-1}\, K^{-1}\right)$