Question

Concentration time data were collected for the following reaction at 30 oC

Answer 1

Answer:

(i) Calculate the average rate of consumption of A in the first 15 seconds of reaction: -8.67X10^(-3) M/s

(ii) Calculate the average rate of production of C in the first 15 seconds of reaction: 0.0.17 M/s

(iii) Calculate the average rate of consumption of A in the last 15 seconds of the reaction: -3x10^(-3) M/s

(iv) Explain the difference between the rates of consumption calculated in (i) and that in (iii): At the beginning the reaction, is fast, then, when time passes, the reaction slows because there are less concentration of the reactants to produce C, so the rate is less.

Explanation:

The general formula to calculate any reaction rate is:

$r=\frac{\Delta [Concentration]}{\Delta t}$

With this formula we can make the calculations, and we can know if r is positive or negative by knowing if we are calculating for a reactant or a product, positive for products, negative for reactants.

(i)

$r=\frac{0.52-0.65}{15}=-8.67x10^{-3} M/s$

(ii)

In this case we need to multiply delta by 2, because 1 mole of A produces 2 moles of C:

$r=2*\frac{0.52-0.65}{15}=-0.017M/s$

As we know it is a product, r needs to be positive, so we change the sign of the result and we have: 0.017 M/s

(iii)

$r=\frac{0.095-0.14}{15}=-3x10^{-3} M/s$

(iv)

Is already answered in the upper part.