Question

A 100.0 mLflask is filled with 0.065 moles of A and allowed to react to form B according to the reaction below. The following experimental data are obtained for the amount of A as the reaction proceeds. What is the average rate of appearance of B in units of M/s between t = 10.0 min. and t = 30.0 min.? Assume that the volume of the flask is constant.

Answer 1

The question is incomplete. The complete question is :

A 100.0 mL flask is filled with 0.065 moles of A and allowed to react to form B according to the reaction below. The following experimental data are obtained for the amount of A as the reaction proceeds. What is the average rate of appearance of B in units of M/s between t = 10 min. and t = 30 min.? Assume that the volume of the flask is constant. A(g) → B(g)

Time 0.0 10.0 20.0 30.0 40.0

Moles of A 0.065 0.051 0.042 0.036 0.031

Solution :

Consider the following reaction as follows :

$A \rightarrow B$

The experiment data is given as follows :

Time (min) :   0.0        10.0       20.0        30.0       40.0

Moles of A :  0.065    0.051    0.042      0.036     0.031

According to the rate of reaction concept, the rate can be expressed as a consumption of the reactant and formation of the product as follows :

Average rate : $= -\frac{d[A]}{dt} = \frac{d[B]}{dt}$

Now we have to calculate the average rate between 10.0 to 30.0 min w.r.t. A as follows :

Rate  $=-\frac{(0.051-0.036) mol \times \frac{1}{0.1 \ L}}{(30.0-10.0) mol \times \frac{60 \ s}{1 \ min}}$

         $=\frac{0.15 \ M}{20 \ min \times \frac{60 \ s}{1 \ min}}$

         $= 1.25 \times 10^{-4 }\ M/s$

Therefore, the rate = $= 1.3 \times 10^{-4 }\ M/s$