Question

For the reaction $A+B\iff C+D$, the initial conc. of A and B are equal . The equilibrium concentration of C is half the initial concentration of A. The equilibrium constant is:

• A. $1$
• B. $1/4$
• C. $9$
• D. $1/9$

Answer 1

The correct option is A $1$

$\begin{array}{cc}& A+B\rightleftharpoons C+D\\ & t=\mathrm{teq}x-ax-a\\ & x-\frac{x}{2}x-\frac{x}{2}\frac{x}{2}\frac{x}{2}\left[c\right]eq=a=\frac{x}{2}\\ & K_C=\frac{\left[C\right]\left[D\right]}{\left[A\right]\left[B\right]}=\frac{x/2\times \frac{x}{2}}{x/2\times x/2}\\ & K_C=1\\ & \text{correct Answer=A}\end{array}$