Part A - Calculating an Average Rate of Reaction If the experiment below is run
ID: 890350 • 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
Explanation / Answer
ANSWER IS E
A ----------------------> B
Initial concentration of A = t=0 sec 1 mole 0
t=20sec 0.54 0.46
t= 40 sec 0.30 0.24
t=60 0.16 0.14
1) after 60 seconds [B] =[0.46+0.24+0.14]
= 0.84 TRUE
2) t= 0 to t=20 Decrease in no of mole of A = 0.46
t= 20 to t=40 Decrease in no of mole of A = 0.24
STATEMENT 2 ALSO TRUE
3) Rate = - [ 0.24-046]/[40-20]
= 7x10-3 seconds
= statement 3 also true
All the statements are true