Chemistry: Mechanisms

Question

The decomposition of hydrogen peroxide in the presence of potassium iodide is believed to occur by the following mechanism:

step 1  slow:  H₂O₂ + I^-  H₂O + OI^-

step 2  fast:   H₂O₂ + OI^-  H₂O + O₂ + I^-

(1) What is the equation for the overall reaction? Use the smallest integer coefficients possible. If a box is not needed, leave it blank.

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(2) Which species acts as a catalyst? _____Enter formula. If none, leave box blank: 

(3) Which species acts as a reaction intermediate? ______Enter formula. If none, leave box blank: 

(4) Complete the rate law for the overall reaction that is consistent with this mechanism.

(Use the form k[A]^m[B]ⁿ... , where '1' is understood (so don't write it) for m, n etc.)

Rate = ________

Answer 1

H₂O₂ + I^- ==> H₂O + OI^- step 1...slow step

H₂O₂ +OI^- ==> H₂O + O₂ + I^- step 2...fast step

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2H₂O₂ ==> 2H₂O + O₂ ... equation for the overall reaction (sum the 2 elementary steps)

(2) I^-__

(3) OI^-

(4) Rate = k[H₂O₂]