---
title: "Homogeneous catalysis"
subject: "Engineering Chemistry"
chapter: 2
key: "semester_2/engineering_chemistry:homogeneous-catalysis"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/homogeneous-catalysis
site: BCT Engineering
---

# Homogeneous catalysis

Engineering Chemistry · Chapter 2: Catalyst

- Asked in: 2069 Bhadra, 2 marks; 2068 Magh, 2 marks (asked 2 times)
- Video: [Difference Between Homogeneous Catalysis and Heterogeneous Catalysis  - Surface Chemistry](https://www.youtube.com/watch?v=lWVX2ofyOIY) — Ekeeda
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/homogeneous-catalysis
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-2

## Question

Explain the term: Homogeneous catalysis.

## Short answer

Homogeneous catalysis occurs when catalyst and reactants are in the same phase. Example: 2SO₂+O₂→2SO₃ catalysed by NO gas, or acid hydrolysis of ester. The catalyst forms an unstable intermediate compound, lowering activation energy.

## Answer

**Homogeneous catalysis** is a catalytic process in which the catalyst and the reactants are in the same phase (all gaseous or all in one solution), forming a single homogeneous mixture.

**Examples:**
- 2SO₂(g) + O₂(g) → 2SO₃(g), catalyst NO(g) (lead chamber process; all gaseous)
- CH₃COOCH₃(l) + H₂O(l) → CH₃COOH + CH₃OH, catalyst H⁺ (acid hydrolysis of ester, all in solution)
- C₁₂H₂₂O₁₁ + H₂O → C₆H₁₂O₆ + C₆H₁₂O₆, catalyst H⁺ (inversion of cane sugar)

Such catalysis is best explained by the intermediate compound formation theory: the catalyst forms an unstable intermediate with a reactant, which then reacts to give the product and regenerates the catalyst. It is easy to control and gives good selectivity, but separating the catalyst from the products is difficult.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. In homogeneous catalysis, the catalyst and the reactants are:
   A. In different phases, with a solid catalyst
   B. In the same phase, forming one homogeneous mixture
   C. Both solids mixed together
   D. Always gases only, never in solution
   Answer: B. Homogeneous catalysis has catalyst and reactants in a single phase (all gas or all in one solution). (Key point: Homogeneous catalysis definition)

2. Which reaction is an example of homogeneous catalysis?
   A. N2 + 3H2 -> 2NH3 with solid Fe
   B. Vegetable oil + H2 -> ghee with solid Ni
   C. 2SO2(g) + O2(g) -> 2SO3(g) with NO(g) (lead chamber process)
   D. 4NH3 + 5O2 -> 4NO + 6H2O with Pt gauze
   Answer: C. In the lead chamber process, the NO catalyst and the reactants are all gases, so it is homogeneous. The others use solid catalysts. (Key point: Example of homogeneous catalysis)

3. Which theory best explains homogeneous catalysis?
   A. Intermediate compound formation theory
   B. Adsorption theory
   C. Collision theory only
   D. Le Chatelier's principle
   Answer: A. The catalyst forms an unstable intermediate with a reactant and is regenerated, which suits single-phase catalysis. (Key point: Theory for homogeneous catalysis)

4. What is the main disadvantage of homogeneous catalysis?
   A. It has poor selectivity
   B. It is hard to control
   C. The catalyst is consumed in the reaction
   D. Separating the catalyst from the products is difficult
   Answer: D. Because catalyst and products are in the same phase, separation is difficult, although such catalysis is easy to control and selective. (Key point: Drawback of homogeneous catalysis)

## Related in Engineering Chemistry

- [Homogeneous/heterogeneous catalysis; intermediate compound theory](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Ahomo-hetero-intermediate) — Engineering Chemistry, chapter 2
- [Promoters in catalysis](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Acatalyst-promoters) — Engineering Chemistry, chapter 2