Question

In this case we have
$A\to B+C$
Time t $\infty$
Total $pres{s}^r$ $P_2$ $P_3$
Find k?

• A. $k=\frac{1}{t}ln\frac{P_3}{2(P_3-P_2)}$
• B. $k=\frac{1}{t}ln\frac{P_3}{2(P_3+P_2)}$
• C. $k=\frac{1}{t}ln\frac{P_2}{2(P_3-P_2)}$
• D. $k=\frac{1}{t}ln\frac{P_2}{2(P_3+P_2)}$

Answer 1

The correct option is A $k=\frac{1}{t}ln\frac{P_3}{2(P_3-P_2)}$

Let P be the initial pressure of A and x be the change in the pressure of A to reach equilibrium.

When time $t=\infty P=\frac{P_3}{2}$

When time is t, the total pressure $P-x+x+x=P+x=P_{2}x=P_2-P=P_2-\frac{P_3}{2}P-x=\frac{P_3}{2}-[P_2-\frac{P_3}{2}]=P_3-P_2$

$k=\frac{1}{t}ln\frac{P}{P-x}$

$k=\frac{1}{t}ln\frac{\frac{P_3}{2}}{(P_3-P_2)}$

$k=\frac{1}{t}ln\frac{P_3}{2(P_3-P_2)}$