Question

In a system : $A\left(s\right)\rightleftharpoons 2B\left(g\right)+3C\left(g\right)$ if the concentration of C at equilibrium is increased by a factor 2, it will cause the equilibrium concentration B to change by:

• A. Two times of its original value
• B. One half of its original value
• C. $2\sqrt{2}$ times of its original value
• D. $\frac{1}{2\sqrt{2}}$ times of its original value

Answer 1

The correct option is D $\frac{1}{2\sqrt{2}}$ times of its original value

$A\left(s\right)\rightleftharpoons 2B\left(g\right)+3C\left(g\right)$
$\therefore K_c=\left[C{]}^3\right[B{]}^2$
If [C] becomes twice, let [B] become [B'], then
$K_c=\left(2C{)}^3\right(B^{\prime }{)}^2\text{or}\left[C{]}^3\right[B{]}^2=\left(2C{)}^3\right(B^{\prime }{)}^2$
$\therefore \frac{\left[B^{\prime }\right]}{\left[B\right]}=\sqrt{\frac{1}{8}}=\frac{1}{2\sqrt{2}}$