4.20   For the decomposition of azoisopropane to hexane and nitrogen at 543K, the following data are obtained.

            

          Calculate the rate constant.

Answers (1)
M manish

Decompostion is represented by equation-


After t time, the total pressure p_{T}p_{0}-p+(p+p) = p_{0}+p

                                               So, p = p_{t}-p_{0}

thus, p_{0}-p = 2p_{0}-p_{t}

for first order reaction,

k= \frac{2.303}{t}\log\frac{p_{0}}{p_{0}-p}
   = \frac{2.303}{360}\log\frac{p_{0}}{2p_{0}-p_{t}}
now putting the values of pressures,

when t =360sec

= \frac{2.303}{360}\log\frac{35}{2*35-54}
= 2.175\times 10^{-3}s^{-1}

when t = 270sec

= \frac{2.303}{270}\log\frac{35}{2*35-54}
= 2.235\times 10^{-3}s^{-1}

So, k_{avg}=k_{1}+k_{2}/2
                 =2.21\times 10^{-3}\ s^{-1} 

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