Catalysts are substances that increase the rate of reaction but can be recovered unchanged at the end of the reaction. Catalysts can be classified as either homogeneous (same state as reactants) or heterogeneous (different state than reactants).

Platinum is used to catalyze the hydrogenation of ethylene:

H2 (g) + CH2CH2 (g) - ⟶Pt (s) CH3CH3 (g)

Chlorofluorocarbons (CFCs) catalyze the conversion of ozone (O3) to oxygen gas (O2):

2O3 (g) - ⟶CFC (g) 3O2 (g)

Magnesium catalyzes the disproportionation of hydrogen peroxide to produce water and oxygen:

2H2O2 (aq) - ⟶Mg (s) 2H2O (l) + O2 (g)

What type of catalysts are platinum, CFCs, and magnesium under these conditions?

- Platinum acts as a heterogeneous catalyst in the hydrogenation of ethylene.

- CFCs act as homogeneous catalysts in the conversion of ozone to oxygen gas.

- Magnesium acts as a heterogeneous catalyst in the disproportionantion of hydrogen peroxide.

Explanation:

Hello,

For the given reactions, considering the definition of homogeneous and heterogeneous catalyst, we can identify that is each catalyst behave as follows:

- Platinum acts as a heterogeneous catalyst in the hydrogenation of ethylene as all the reactants are gaseous but it remains solid.

- CFCs act as homogeneous catalysts in the conversion of ozone to oxygen gas as it remains gaseous as well as both ozone and oxygen.

- Magnesium acts as a heterogeneous catalyst in the disproportionantion of hydrogen peroxide as it is solid whereas the other species are aqueous, liquid and gaseous

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