Chemical Kinetics - Result Question 58

####58. $2 X(g) \longrightarrow 3 Y(g)+2 Z(g)$

Time
(in min)
0 100 200
Partial pressure of
$\boldsymbol{X}$ (in mm of $Hg$ )
800 400 200

Assuming ideal gas condition. Calculate

(a) order of reaction

(b) rate constant

(c) time taken for $75 %$ completion of reaction

(d) total pressure when $p _x=700 mm$

$(2005,4 M)$

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Answer:

Correct Answer: 58. $(20.74 min)$

Solution:

  1. (a) Partial pressure becomes half of initial in every $100 min$, therefore, order $=1$.

(b) $k \times 100=\ln \frac{800}{400}=\ln 2 \Rightarrow k=6.93 \times 10^{-3} min^{-1}$

(c) For 75% reaction; time required $=2 \times$ half-life $=200 min$

(d) $2 X(g) \longrightarrow 3 Y(g)+2 Z(g)$

$$ \begin{aligned} & 800-x \quad \frac{3}{2} x \ & \text { Total pressure }=800+\frac{3}{2} x \ & \text { Also } 800-x=700 \Rightarrow x=100 \ & \Rightarrow \text { Total pressure }=800+\frac{3}{2} \times 100=950 mm Hg \end{aligned} $$



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