Question

The reaction A(g) + 2B(g) $\rightarrow$ C(g) is an elementary reaction. In an experiment involving this reaction, the initial partial pressures of A and B are PA = 0.40 atm and PB = 1.0 atm respectively. When pressure of C becomes 0.3 atm in the reaction the rate of the reaction relative to the initial rate is :

• A. $\frac{1}{12}$
• B. $\frac{1}{50}$
• C. $\frac { 1 } { 25 }$
• D. None of these

Answer 1

Answer: (C)

$\frac { 1 } { 25 }$

Answer 2

}{\text{t = 0} \text{0.4 atm} \text{1 atm} \text{0 atm} }$$$\text{t = t} (\text{0.4 -0.3})\text{atm} (\text{1 - 0.6})\text{atm} \text{0.3 atm}$Since reaction is elementary. So, Rate of reaction w.r.t. A & B will be of order equal to stoichiometric coefficient $${\text{Rate = K }\lbrack A\rbrack\ \lbrack B\rbrack^{2} }{\text{Rate}(\text{Initial})\text{ = K }\lbrack\text{0.4}\rbrack\ \lbrack 1\rbrack^{2} }{\text{Rate}(\text{aftar t = t})\text{ = K }\lbrack\text{0.1}\rbrack\lbrack\text{0.4}\rbrack^{2}}$$ $$\frac{R_{(t = t)}}{R_{(t = 0)}} = \frac{K\lbrack 0.1\rbrack\lbrack 0.4\rbrack^{2}}{K\lbrack 0.4\rbrack\lbrack 1\rbrack} = \frac{1}{25}$$