Part A - Calculating an Average Rate of Reaction If the experiment below is run

ID: 891112 • Letter: P

Question

Part A - Calculating an Average Rate of Reaction

If the experiment below is run for 60 s, 0.16 mol A remain. Which of the following statements is or are true?

I. After 60 s there are 0.84 mol B in the flask.

II. The decrease in the number of moles of A from t1 = 0 to t2 = 20 s is greater than that for t1 = 40 to t2 = 60 s.

III. The average rate for the reaction from t1 = 40 to t2 = 60 s is 7.0×103 M/s.

A) Only one of these statements is true

B) Statements I and II are true

C) Statements I and III are true

D) Statements II and III are true

E) All three statements are true

Solution :-

Part A average rate of reaction

Initial rate = -Delta [A]/ delta T

= -[-0.54-1.00]/20-0 s

= 0.023 mol-1 s-1

Second rate = -[A]/delta T

=-[0.30-0.54]/40-20

= 0.012 mol -1 s-1

Average rate = 0.023 + 0.012 / 2 = 0.0175 mol-1 s-1

Part ll

Only one statement of these statement is true

That is

The decrease in the number of moles of A from t1 = 0 to t2 = 20 s is greater than that for t1 = 40 to t2 = 60 s