Question

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

• 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

Answer: (D)

For $A(s)\rightleftharpoons 2B(g)+3C(g)$

$\therefore K_c=[C{]}^3[B{]}^2$ ; if $[C]$ becomes twice,

Then let conc. of $B$ becomes $B^{\prime }$, then

$K_c=[2C{]}^3{\left[B^{\prime }\right]}^2$

or $[C{]}^3\cdot [B{]}^2=[2C{]}^3\cdot {\left[B^{\prime }\right]}^2$

$\therefore \frac{\left[B^{\prime }\right]}{[B]}=\frac{1}{8}=\frac{1}{2\sqrt{2}}$