Question

\[\mathop {{{\rm{C}}_{{\rm{12}}}}{{\rm{H}}_{{\rm{22}}}}{{\rm{O}}_{{\rm{11}}}}}\limits_{{\rm{Sucrose}}} + {{\rm{H}}_{\rm{2}}}{\rm{O}} \overset{Dil.H_{2}SO_{4}}{\rightarrow} \mathop {{{\rm{C}}_{\rm{6}}}{{\rm{H}}_{{\rm{12}}}}{{\rm{O}}_{\rm{6}}}}\limits_{{\rm{Fructose}}} \left( {aq} \right) + \mathop {{{\rm{C}}_{\rm{6}}}{{\rm{H}}_{{\rm{12}}}}{{\rm{O}}_{\rm{6}}}}\limits_{{\rm{Glucose}}} \left( {aq} \right)\]
In this reaction, dilute \[{{\rm{H}}_{\rm{2}}}{\rm{S}}{{\rm{O}}_{\rm{4}}}\] is called
A: Homogeneous catalysis
B: Homogeneous catalyst
C: Heterogeneous catalysis
D: Heterogeneous catalyst

Answer 1

Hint: The rate of a chemical reaction is affected by a catalyst. A catalyst speeds up a reaction by reducing the activation energy. Some examples of catalysts are nickel, platinum, iron, manganese dioxide etc.

Complete Step by Step Answer:
Let's understand homogeneous and heterogeneous catalysts in detail. In homogeneous catalysis, the presence of the reactants and catalyst is in the same phase, generally liquid. One example of homogeneous catalysis is the reaction of sulfur dioxide and oxygen to give sulphur trioxide using NO catalyst.
\[2{\rm{S}}{{\rm{O}}_{\rm{2}}}\left( g \right) + {{\rm{O}}_{\rm{2}}}\left( g \right) \overset{NO}{\rightarrow} 2{\rm{S}}{{\rm{O}}_{\rm{3}}}\left( g \right)\]

Here, NO is also in gaseous phase.

In heterogeneous catalysis, the catalyst and the reactions are present in different phases. For example, the oxidation of ammonia to form NO in presence of a platinum catalyst is heterogeneous catalysis. For example,

\[{\rm{N}}{{\rm{H}}_{\rm{3}}}\left( g \right) + 5{{\rm{O}}_{\rm{2}}}\overset{Pt}{\rightarrow}\left( g \right)4{\rm{NO}}\left( g \right){\rm{ + 6}}{{\rm{H}}_2}{\rm{O}}\left( g \right)\]

Here the given reaction is the hydrolysis of sugar. The reactants are sucrose and water. And the catalyst is dilute sulphuric acid. So, the reactants and sulphuric acid are in the same phase that is, liquid.
Therefore, this catalysis reaction is of homogenous nature and sulphuric acid is a homogeneous catalyst.
Therefore, option B is right.

Note: The role of the catalyst is to speed up both forward and backward reactions. Thus, it helps to achieve the equilibrium state early. But the concentration at equilibrium is not changed, that is, the equilibrium constant is not changed. Catalysts are classified as positive and negative catalysts. Positive catalysts function in speeding up of reaction. And negative catalysts lower the reaction rate.