Which of the following is an example of heterogeneous catalysis?

A. An aqueous acid reacts with a solid metal.
B. Ethylene and hydrogen gases are adsorbed onto the surface of a metal catalyst to accelerate the formation of ethane.
C. An enzyme catalyzes a biochemical reaction inside a human muscle cell.
D. An enzyme catalyzes a biochemical reaction that produces the alcohol and CO2 gas in beer.

Question

Which of the following is an example of heterogeneous catalysis?

 		A.	An aqueous acid reacts with a solid metal.
 		B.	Ethylene and hydrogen gases are adsorbed onto the surface of a metal catalyst to accelerate the formation of ethane.
 		C.	An enzyme catalyzes a biochemical reaction inside a human muscle cell.
 		D.	An enzyme catalyzes a biochemical reaction that produces the alcohol and CO2 gas in beer.

vera_ewing · Answer

@mathmate Can you help me please?

mathmate · Answer

Hints:

Many (multiple choice) problems can be solved by understanding perfectly the definition of the terms involved.  If you have difficulties with a problem, start by googling the definition of the terms.  Very often, you will find the answer in the definition itself.
For example, the definition of "heterogeneous catalysis" is defined (by Wiki) as:
"In chemistry, heterogeneous catalysis refers to the form of catalysis where the phase of the catalyst differs from that of the reactants."

"phase" here refers to the state of the matter, be it gas, liquid or solid.

vera_ewing · Answer

Hmm, okay, so is the answer A?

mathmate · Answer

You're getting the idea, but where's (or what's) the catalyst in A?

vera_ewing · Answer

The aqueous acid?

mathmate · Answer

In A, both the acid and metal are reactants, according to the text.
Catalysts do not take part in the reaction, or at least, the quantity of catalyst does not change at the end of the reaction.  Here the acid will be used up, so it is not a catalyst.  In short, they have not specified the nature of the catalyst in A.

vera_ewing · Answer

So is the answer C?

mathmate · Answer

Do you know what enzymes are?

vera_ewing · Answer

Yes

mathmate · Answer

Enzymes are basically acting as catalysts, but are they usually gas, liquid or solid (in the animal's cells)?

vera_ewing · Answer

They're the liquid right?

mathmate · Answer

Right, so are the ingredients in the cells.  Would that make a heterogeneous catalyst (refer back to the definition if necessary)?

vera_ewing · Answer

Yes it would make it heterogeneous.

mathmate · Answer

"In chemistry, heterogeneous catalysis refers to the form of catalysis where the phase of the catalyst $differs$ from that of the reactants."

mathmate · Answer

@vera_ewing 
Knowing the definition of  heterogeneous catalysis, you will need to read $every$ option and choose the one that fits the bill.  Do not make a guess and stick to it.