Question

One mole of $N_2{O}_4\left(g\right)$ at 300K is kept in a closed container under 1 atomsphere. It is heated to 600K when 20% by mass of $N_2{O}_4\left(g\right)$ decomposes to $N{O}_2\left(g\right)$. The resultant pressure is:

• A. 1.2 atm
• B. 2.4 atm
• C. 2 atm
• D. 5 atm

Answer 1

The correct option is B 2.4 atm

$\begin{array}{ccc}& n_2{O}_4& 2N{O}_2\\ & 1& 0\\ Ateq.& 1-0.2& 0.4\\ & 0.8& 0.4\end{array}$
Also initial pressure of $N_2{O}_4$ before dissociation increases to 2 atm on heating from 300 to 600K.
P $\alpha$ No. of moles
2 atm $\alpha$ 1 mole
Final pressure $\alpha$ Final total no. of moles(0.8+0.4=1.2)
Final pressure= 2 atm $\times$ 1.2 = 2.4 atm