Question

The decomposition of benzene diazonium chloride C6H5N2Cl -> C6H5Cl + N2 follows first order kinetics with a rate constant of 4.3 x 10-5 s-1 at 20 °C. If the initial partial pressure of C6H5N2Cl is 0.088 atm, calculate its partial pressure after 10.0 hours. What is the half-life for this reaction?

Answer 1

C6H5N2Cl -----------------------------> C6H5Cl + N2

0.088                                                   0             0

0.088 -x                                               x              x

for first order

t = 10 h = 10 x 60 x 60 = 36000 sec

k = 1/t ln (Po /Pt)

4.3 x 10^-5 = 1/ 36000 ln (0.088 / Pt)

Pt = 0.0187

after 10 hours its partial pressure = 0.0187 atm

half life = 0.693 / k

             = 0.693 / 4.3 x 10^-5

            = 16116 sec