Question

Find the change in internal energy of 60 g of Argon gas when its change in temperature is 200 K.
(Given degree of freedom of argon is 3 and its molar mass = 40 g/mole)

• A. $4800.3J$
• B. $3741.3J$
• C. $1250.4J$
• D. $3500.2J$

Answer 1

The correct option is B $3741.3J$

Since,
we know $\Delta U=\frac{f}{2}nRdT$
where $\Delta U$= internal energy of the gas
n = number of moles of gas $\therefore n=\frac{60}{40}=1.5mole$
We know, f = degree of freedom = 3 (Given)
$\Delta U=\frac{3}{2}\times 1.5\times 8.314\times \Delta T$
So, $\Delta U=\frac{3}{2}\times 1.5\times 8.314\times 200$

$\Rightarrow \Delta U=3741.3J$