Q.

For the thermal decomposition of N2O5(g) at constant volume, the following table can be formed, for the reaction mentioned below:

2N2O5(g)2N2O4(g)+O2(g)

Sr. No. Times Total Pressure (atm)
1 0 0.6
2 100 'x'


x = _____ ×10-3 atm (nearest integer)

Given: Rate constant for the reaction is 4.606×10-2s-1.                            [2025]


Ans.

(897)

2N2O5(g)2N2O4(g)+O2(g)t=0 p°00t=100sp°-2p2pp

Total pressure at t=0 is p°+0+0=p°=0.6

Total pressure at t=100s is (p°-2p)+2p+p=p°+p=x

From above two equations, p=x-0.6

For first order reaction, rate constant is given as:

                     k=2.303tlogPN2O5(t=0)PN2O5(t=t)

4.606×10-2=2.303100log0.60.6-2(x-0.6)

4.606×10-2=2.303100log0.61.8-2x

log0.61.8-2x=2

0.61.8-2x=102=100

1.8-2x=0.006

x=0.897 atm=897×10-3atm