Question

Consider a reaction $A\left(g\right)\to 3B\left(g\right)+2C\left(g\right)$ with rate constant $1.386\times {10}^{-2}mi{n}^{-1}$. Starting with 2 moles of A in a 12.5 litre vessel initially. If the reaction is allowed to take place at constant pressure & at 298K then find the concentration of B after 100 min.

• A. 0.04 M
• B. 0.36 M
• C. 0.09 M
• D. None of these

Answer 1

Answer: (B)

0.36 M

Given that,

$A_0=0.16M$

Then, from the unit of rate constant we get the order of the reaction is first order.

Now,

$A=A_0{e}^{-kt}$

$A=0.16e^{-1.386\times 100\times {10}^{-2}}$

$=0.04$M

$\therefore$ $B=3\Delta A=3\times (0.16-0.04)=0.36M$