Consider this reaction:

2Cl2O5 (g)-->2Cl2(g) +5O2 (g)

At a certain temperature it obeys this rate law.

rate= (17.4 M -1 .s -1 ) [Cl2O5]2

Suppose a vessel contains Cl2O5 at a concentration of 1.46M. Calculate the concentration of Cl2O5 in the vessel .400 seconds later. You may assume no other reaction is imporant. Round your answer to 2 significant digits.

0.13 M ( 2 s.f)

Explanation:

2Cl2O5 (g)-->2Cl2(g) +5O2 (g)

rate= (17.4 M -1 .s -1 ) [Cl2O5]2

From the rte above, we can tell that our rate constant (k)  = 17.4 M -1 .s -1

The units of k tells us this is a second order reaction.

Initial Concentration  [A]o = 1.46M

Final Concentration  [A] = ?

Time = 0.400s

The integrated rate law for second order reactions is given as;

1 / [A] = (1 / [A]o) + kt

1 /  [A] = [ (1/ 1.46) + (17.4 * 0.4) ]

1 /  [A] = 0.6849 + 6.96

1 /  [A] = 7.6496

[A] = 1 / 7.6496

[A] = 0.13073 M ≈ 0.13 M ( 2 s.f)

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