CALCULATING AVERAGE RATE and STOICHIOMETRY

Last Wednesday we learned about Calculating the Average Rate and reaction Stoichiometry.

AVERAGE RATE & CALCULATING AVERAGE RATE

The numerical value for the rate of a reaction can be determined by examining the change in the amount of a substance at a particular time, or over a period of time.

The average rate for a reaction is given by the following equation:

The following is an example of calculating the average rate of a substance:

What is the average rate over the entire 27 seconds?

Rate = X ÷ T

Rate = (Final concentration of X) - (initial concentration of X)
               ______________________________________
               final time - initial time

Rate = (1 mol/L - 0.0 mol/L)/(27 s - 0 s)

Rate = 1 mol/L ÷ 27 s

Rate = .037 mol/Ls

RATE AND STOICHIOMETRY

Rate of creation of products or disappearance of reactants can be predicted from reaction stoichiometry.

We'll use 2NO2 ---> 2NO + O2 as an example

The rate of decomposition of NO2, is equal to the production of NO. The ratio is 1:1. This shows that as one molecule of NO2 is decomposed, one molecule of NO is produced.

The rate of production of Oxygen is half that of the NO. The ratio is 2:1. The rate production of NO should be twice that of the oxygen.

Therefore,

On the same day Mrs. Kozoriz handed out some worksheets and here are the answers for Questions 1 - 3

Ask Mrs. Kozoriz for the work sheets if you missed Wednesday's class.

ALDRIN to scribe for Friday