Question

Which of the following is an example of heterogeneous catalysis?
A. $4N{{H}_{3(g)}}+5{{O}_{2(g)}}\xrightarrow{P{{t}_{(s)}}}4N{{O}_{(g)}}+6{{H}_{2}}{{O}_{(g)}}$
B. $2S{{O}_{2}}+{{O}_{2}}\xrightarrow{N{{O}_{(g)}}}2S{{O}_{3}}$
C. $C{{H}_{3}}COOC{{H}_{3(l)}}+{{H}_{2}}O\xrightarrow{HC{{l}_{(aq)}}}C{{H}_{3}}COOH+C{{H}_{3}}OH$
D. ${{C}_{12}}{{H}_{22}}{{O}_{11}}+{{H}_{2}}O\xrightarrow{{{H}_{2}}S{{O}_{4}}}{{C}_{6}}{{H}_{12}}{{O}_{6}}+{{C}_{6}}{{H}_{12}}{{O}_{6}}$

Answer 1

Hint: A catalyst is a material that can be added to a mixture without being used in the process to increase the reaction rate. Catalysts are useful because they increase the rate of a reaction without themselves being consumed and are therefore reusable.

Complete answer:
Heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reactants or products. Phase distinguishes between not just elements of solid , liquid and gas, but also immiscible mixtures (e.g., oil and water), or anywhere an interface occurs. Heterogeneous catalysis usually requires catalysts for the solid phase and reactants of the gas phase.
Homogeneous catalysis refers to reactions where, mostly in solution, the catalyst is in the same step as the reactants. The term is almost exclusively used for defining solutions and includes catalysis of organometallic compounds.

A. $4N{{H}_{3(g)}}+5{{O}_{2(g)}}\xrightarrow{P{{t}_{(s)}}}4N{{O}_{(g)}}+6{{H}_{2}}{{O}_{(g)}}$
In this reaction, reactants are in the gas phase whereas catalysts are in the solid phase. Hence the reaction is an example of heterogeneous catalysis.

B. $2S{{O}_{2}}+{{O}_{2}}\xrightarrow{N{{O}_{(g)}}}2S{{O}_{3}}$
In this reaction, reactants and catalysts are in the gas phase. Hence the reaction is an example of homogeneous catalysis.

C. $C{{H}_{3}}COOC{{H}_{3(l)}}+{{H}_{2}}O\xrightarrow{HC{{l}_{(aq)}}}C{{H}_{3}}COOH+C{{H}_{3}}OH$
In this reaction, reactants and catalysts are in a liquid phase. Hence the reaction is an example of homogeneous catalysis.

D. ${{C}_{12}}{{H}_{22}}{{O}_{11}}+{{H}_{2}}O\xrightarrow{{{H}_{2}}S{{O}_{4}}}{{C}_{6}}{{H}_{12}}{{O}_{6}}+{{C}_{6}}{{H}_{12}}{{O}_{6}}$
In this reaction, reactants and catalysts are in a liquid phase. Hence the reaction is an example of homogeneous catalysis.
Hence, option A is an example of heterogeneous catalysis.
So, the correct answer is “Option A”.

Note: Don’t get confused between heterogeneous catalysis and homogeneous catalysis.
Heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reactants or products whereas Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants, principally in solution.