Which of the following is an example of heterogeneous catalysis?
A. Ethylene and hydrogen gases are adsorbed onto the surface of a metal catalyst to accelerate the formation of ethane.
B. An enzyme catalyzes a biochemical reaction that produces the alcohol and CO2 gas in beer.
C. An aqueous acid reacts with a solid metal.
D. An enzyme catalyzes a biochemical reaction inside a human muscle cell.
To determine which of the options is an example of heterogeneous catalysis, let's first understand what heterogeneous catalysis is.
Heterogeneous catalysis involves a catalyst that exists in a different phase (solid, liquid, or gas) from the reactants. The catalyst and reactants are not in the same state. The reactant molecules adsorb onto the surface of the catalyst, undergo a reaction, and then desorb from the catalyst's surface.
With this definition in mind, let's examine each option:
A. Ethylene and hydrogen gases are adsorbed onto the surface of a metal catalyst to accelerate the formation of ethane.
This option describes the reactant gases (ethylene and hydrogen) being adsorbed onto the surface of a metal catalyst to catalyze the formation of ethane. Since the catalyst is in a different phase (solid) from the reactant gases, this option represents an example of heterogeneous catalysis.
B. An enzyme catalyzes a biochemical reaction that produces alcohol and CO2 gas in beer.
This option describes the catalytic action of an enzyme in a biochemical reaction that produces alcohol and CO2 gas in beer. Enzymes are generally considered to be homogeneous catalysts because they are typically present in the same phase as the reactants. Therefore, this example does not represent heterogeneous catalysis.
C. An aqueous acid reacts with a solid metal.
This option describes a reaction between an aqueous acid and a solid metal. Since both the acid and metal are in the same phase (whether solid, liquid, or gas), this option does not represent heterogeneous catalysis.
D. An enzyme catalyzes a biochemical reaction inside a human muscle cell.
Similar to option B, this option also describes the catalytic action of an enzyme in a biochemical reaction. Since the enzyme is present inside a human muscle cell, it is not a different phase from the reactants. Therefore, this option does not represent heterogeneous catalysis.
Based on the information above, the correct answer is A. Ethylene and hydrogen gases are adsorbed onto the surface of a metal catalyst to accelerate the formation of ethane.