Question

$A+3B\rightleftharpoons 2C+D$
For this hypothetical reaction, initial moles of $A$ is twice that of $B$. If at equilibrium moles of $B$ and $C$ are equal then percent of $B$ reacted is:

• A. $10\%$
• B. $20\%$
• C. $40\%$
• D. $60\%$

Answer 1

The correct option is D $60\%$

$\begin{array}{cccccccc}& A& +& 3B& \rightleftharpoons & 2C& +& D\\ \text{Initially}& 2a& & a& & 0& & 0\\ \text{At eqbm}& 2a-x& & a-3x& & 2x& & x\end{array}$
and $a-3x=2xx=a/5$
Moles of $B$ reacted $=\frac{3x}{a}\times 100=\frac{3}{5}\times 100=60\%$