Question

The above reaction was started with 10 moles of $A\left(s\right)$ at constant temperature and pressure conditions. After completion of reaction $\frac{\left[B\right]}{\left[D\right]}=\frac{2}{1}$. Then, which of the following is/are correct?

• A. Moles of $A$ reacting in $1^{st}$ reaction is 5
• B. Moles of $C$ formed after the reaction completion is 10
• C. Work done by the system at constant pressure and temperature condition is $20RT$
• D. Work done by the system at constant pressure and temperature condition is $25RT$

Answer 1

Answer: (A), (B), (D)

The correct options are
A Moles of $A$ reacting in $1^{st}$ reaction is 5
B Moles of $C$ formed after the reaction completion is 10
D Work done by the system at constant pressure and temperature condition is $25RT$

$A\left(s\right)\to 2B\left(g\right)$ ; $A\left(s\right)\to 2C\left(g\right)+D\left(g\right)$
$x$ $10-x$
- $2x$ - $2(10-x)$ $10-x$

Now after completion of reaction $\frac{\left[B\right]}{\left[D\right]}=\frac{2}{1}$

$\Rightarrow \frac{2x}{10-x}=\frac{2}{1}$

$x=5$

$\therefore$ Moles of $A$ reacting in $1^{st}$ reaction $=5$

Moles of B formed after the reaction $=2\times 5=10$

Moles of C formed after the reaction $=2\times 5=10$

Work done by the system $=\Delta n_{g}RT=(10+10+5-0)RT=25RT$