One mole of `N_(2)O_(4)(g)` at 300 K is kept in a closed container under one atmosphere. It is heated to 600K when 20% by mass of `N_(2)O_(4)`(g) decomposes to `NO_(2)`(g). The resultant pressure is:

Options

A. 1.2 atm
B. 2.4 atm
C. 2.0 atm
D. 1.0 atm

Answer

B

Explanation

`N_2O_4to2NO_2`
Initial amoles 1
Molews after dissociation 1-0.2 0.4
= 0.8
Total moles after dissociation `=0.8+0.4=1.2`
Initial temp = 300 K
`:." "P_1V=n_1RT_1" or "1xxV=1xxRxx300" ...(i)"`
Temp. after dissociation = 600 K
`:." "P_2V_2=n_2RT_2" or "P_2xxV=1./2xxRxx600" ...(ii)"`
Dividing eqn. (ii) by eqn. (i)
`P_2=(1.2xx600)/(300)=2.4"atm"`