The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume.


SO2Cl2(g)→ SO2 (g) + Cl2 (g)


 



Experiment



Time/s–1



Total pressure/atm



1



0



0.5



2



100



0.6



 


 


 


 


 


 


 


 


Calculate the rate of the reaction when total pressure is 0.65 atm


When t = 0, the total partial pressure is P0 = 0.5 atm



When time t = t, the total partial pressure is Pt = P0 + p


P0-p = Pt-2p, but by the above equation, we know p = Pt-P0


Hence, P0-p = Pt-2(Pt-P0)


Thus, P0-p = 2P0 – Pt


We know that time


Where, k- rate constant


[R]° -Initial concentration of reactant


[R]-Concentration of reactant at time ‘t’


Here concentration can be replaced by the corresponding partial pressures.


Hence, the equation becomes,


equation 1


At time t = 100 s, Pt = 0.6 atm and P0 = 0.5 atm,


Substituting in equation 1,



Thus, k = 2.231 × 10-3 s-1


The rate of reaction R = k × PS02Cl2


When total pressure Pt = 0.65 atm and P0 = 0.5 atm, then


PS02Cl2 = 2P0-Pt


Thus, substituting the values, PS02Cl2 = 2(0.5)-0.6 = 0.35 atm


R = k × PS02Cl2 = 2.231 × 10-3 s–1 × 0.35


Rate of the reaction R = 7.8 × 10-4atm s–1


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