Answered Essay: Chapter 12| Kinetics 702 5. A study of the rate of the reaction represented as 2A → B gave the

To find the instataneous rate of reaction you must do a graph and then draw a tangent line, this line must touch the point (time = 15 s) but must not cross the line graph, then you have to choose some points from it and read the x values and the y values, then you have to do

In your example I´m focussing and graphing the points where time is 10 , 15 and 20 secs.

The brown line is the tangent, it has values of y

y2 = 0.4

y1 = 0.5

X:

x1 = 13.7

x2 = 17.7

Calculate the slope

slope = (0.4 – 0.5 ) / (17.7-13.7 = – 0.025

the – sign is because the reactant is dissapearing, so it is correct to say that the instantaneous rate of dissapearance is 0.025 M/s

C. To calculate the average rate of reaction remember that:

in this case a = 2 and b = 1 so:

So we just need to divide the average rate of reaction you got in the first part (which is correct by the way)

Average rate of formation of B = 0.0375 / 2 = 0.01875 M/s

Instantaneous rate of formation, it follows the same stoichiometrical rule I wrote before:

so the instantaneous rate of formation of B is 0.025 / 2 = 0.0125 M /s

As an extra for you to see the formation of B, i calculated the formation of B from A, the ammount of A that dissapeared is the ammount of B formated dividided by 2.

If you want to practice, try to get the instantaneous rate of formation of B by drawing a tangent line as I did in part b, you should be gettin the slope value of 0.0125 M