Question

The reaction $A\left(g\right)+2B\left(g\right)\to C\left(g\right)+D\left(g\right)$ is an elementary process. In an experiment , the initial partial pressure of A and B are $P_A=0.40$ and $P_B=0.60atm.$ When $P_C=0.2atm$ and the rate of reaction relative to the initial rate is ?

• A. 1/48
• B. 1/24
• C. 9/16
• D. 1/18

Answer 1

Answer: (D)

1/18

Initial partial pressure of A & B is 0.4 and 0.6 respectively
Rate law (initial) = $k\left[0.4\right][0.6{]}^2$ ..............(1)

Now when P(c)=0.2 ........(let say x)
$⟹P\left(a\right)=0.4-x=0.2$
$⟹P\left(b\right)=0.6-2x=0.2$

Therefore rate law(final) = $k\left[0.2\right][0.2{]}^2$ ............(2)
divide eq2 and eq 1, = $\frac{ratelaw\left(final\right)}{ratelaw(initial}$

=1\18