Question

Platinised asbestos is used as a catalyst in the manufacture of ${{H}_{2}}S{{O}_{4}}$ . It is an example of:
(A) homogeneous catalyst
(B) heterogeneous catalyst
(C) autocatalyst
(D) induced catalyst

Answer 1

Sulphuric acid is a strong mineral acid, which is used as fertilizer and manufacturing of chemicals like hydrochloric acid where all reactants and products are same phase except for catalyst , detergents, dyes, pigments, etc. this chemical is also known as carborane acid, because of the strongest high concentrated acid.

Complete answer:
The substance that can alter the rate of a chemical reaction without being involved in the reaction is known as a catalyst and the phenomenon which undergoes reactions is called catalysis.
There are many different types of catalyst as follows,
Homogeneous catalyst: when the phase of the catalyst and reactants and products are the same. Then the catalyst is known as a homogeneous catalyst and the reactions involved by using this catalyst are homogeneous catalysis.
Example: hydrolysis of sugarcane in the presence of dilute sulphuric acid.
${{C}_{12}}{{H}_{22}}{{O}_{11}}(aq)+{{H}_{2}}O(l)\overset{{{H}^{+}}(aq)}{\mathop \to }\,{{C}_{6}}{{H}_{12}}{{O}_{6}}(aq)+{{C}_{6}}{{H}_{12}}{{O}_{6}}(aq)$
Heterogeneous catalyst: when the catalyst has a different phase with reactants, the catalyst is said to a heterogeneous catalyst and this catalysis is named as heterogeneous catalysis.
Example: Platinised asbestos is used as a catalyst in, the manufacture of ${{H}_{2}}S{{O}_{4}}$
In this process reactants and products are in the gas phase and the catalyst is in the solid phase.
Reactants are sulfur dioxide and oxygen. The product is sulfur trioxide. Both are in the gaseous phase, whereas catalyst platinized asbestos is in the solid phase.
$2S{{O}_{2}}(g)+{{O}_{2}}(g)\overset{Pt}{\mathop \to }\,2S{{O}_{3}}(g)$
Induced catalyst: the catalyst which increases the rate of the chemical reaction is known as an induced catalyst or positive catalyst
Auto catalyst: the reaction product also acts as a catalyst is an autocatalyst.
Example: potassium permanganate
So, the Platinised asbestos is used as a catalyst in the manufacture of ${{H}_{2}}S{{O}_{4}}$is a heterogeneous catalyst.

The correct answer is option B.

Note:
A catalyst that decreases the rate of the chemical reaction is called a negative catalyst. This is because this catalyst increases the activation energy by taking a longer alternative path. For example, phosgene gas as a negative catalyst in the oxidation of chloroform and oxidation of sodium sulfate in presence of alcohol.