Catalysis and Rate of Reaction Metals often form several cations with different

Question

Catalysis and Rate of Reaction Metals often form several cations with different charges. Cerium, for example, forms Ce3+ and Ce4+ ions, and thallium forms Tl+ and Tl3+ ions. Cerium and thallium ions react as follows: 2Ce4+(aq)+Tl+(aq)2Ce3+(aq)+Tl3+(aq) This reaction is very slow and is thought to occur in a single elementary step. The reaction is catalyzed by the addition of Mn2+(aq) according to the following mechanism: Ce4+(aq)+Mn2+(aq)Ce4+(aq)+Mn3+(aq)Mn4+(aq)+Tl+(aq)Ce3+(aq)+Mn3+(aq)Ce3+(aq)+Mn4+(aq)Mn2+(aq)+Tl3+(aq)

Part A

What is the rate law for the uncatalyzed reaction?

What is the rate law for the uncatalyzed reaction?

Part B

If the uncatalyzed reaction occurs in a single elementary step, why is it a slow reaction?

Check all that apply.

Check all that apply.

The probability of an effective three-particle collision is low.

Part C

The catalyzed reaction is first order in [Ce4+] and first order in [Mn2+]. Which of the steps in the catalyzed mechanism is rate determining?

The catalyzed reaction is first order in  and first order in . Which of the steps in the catalyzed mechanism is rate determining?

Part D

Based on their available oxidation states, rank the following metals on their ability to catalyze this and other oxidation-reduction reactions.

Rank from best to worst catalyst. To rank items as equivalent, overlap them.

Help

Reset

vanadium

manganese

titanium

Worst catalyst

Best catalyst

rate=k[Ce4+] rate=k[Tl+] rate=k[Ce4+][Tl+] rate=k[Ce4+]2[Tl+] rate=k[Ce4+]2[Tl+]2 rate=k[Ce4+][Tl+]2

Explanation / Answer

A) the rate law for the uncatalyzed reaction

Rate = [Ce+4]2 [Tl+]

The rate of reaction is second order with respect ot Ce+4 while first order with respect to Tl+.

B) An uncatalyzed reaction is slow due to high activation energy, as The reaction requires the collision of three particles with the correct energy and orientation.

C) Ce4+(aq)+Mn2+(aq)?Ce3+(aq)+Mn3+(aq)

The order of reaction depends upon the reactants

The rate expression will be

Rate = K[Ce4+][Mn2+]

D) the best to worst catalyst order will be

Manganese then Vanadium then Titanium

This is based on Irving and Williams series

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