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shiwani sharma Grade:

for the first order reaction

A(g) ------: 2B(g) +C(g)

the initial pressure is Pa= 90 mm hg and pressure after 10 min. is 180 mm of hg. find the rate constant.ans is 1.15*10^-3

6 years ago

Answers : (2)

vikas askiitian expert
510 Points

A           =>           2B   +   C

p                           0         0                        (initial)                     (at t=0)

P-Po                     2Po       Po                       (final)                       (at t =10)

initial total pressure = P = 90mm

final total pressure = 180mm

 from eq adding all presures we get total pressure = P + 2Po

P +  2Po = 180

90 + 2Po = 180

   Po = 45

for A , initially pressure  = P= 90

        final pressure = P-Po =  90-45 = 45

rate constant (k) = 2.303 log(Pi/Pf) / t

                        = 2.303 log90/45 / t


                        k = 0.069 min-1

this value of rate constant is in min-1 , 1min = 60sec so

                   K = 0.069/60 sec-1  = 1.15*10-3 sec-1

approve if u like my ans

6 years ago
879 Points

Dear student.,

Write the rate of reation in terms of pressure

r=(2.303log P/Po)/time

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Askiitians Expert

Sagar Singh

B.Tech, IIT Delhi

6 years ago
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