MHT-CET Chemistry · Surface Chemistry
Catalysis: Homogeneous and Heterogeneous, Promoters and Inhibitors, and Nanomaterials
A catalyst changes the rate of a reaction without being used up; it may share the reactants' phase or not, can be helped by a promoter or opposed by an inhibitor, and works best when finely divided — which is why nanomaterials make good catalysts.
Why this matters
6 PYQs, none HARD. Three name a catalyst's role or type — K₂O in the Haber process, glycerol with H₂O₂, nickel in hydrogenation; three are about nanomaterials — TiO₂ in photocatalysis, what SEM measures, and nano properties. Two cards.
Concept 1 of 2: Homogeneous and Heterogeneous Catalysis, Promoters and Inhibitors
Definition
- Homogeneous: catalyst and reactants in one phase — SO₂ oxidised with NO (gases); sugar hydrolysed with aqueous H₂SO₄.
- Heterogeneous: different phases — solid Ni hydrogenating liquid oil; Fe in the Haber process; Pt/V₂O₅ in the contact process.
- Promoter: raises a catalyst's efficiency — K₂O and Al₂O₃ for Fe in the Haber process; Mo as well.
- Inhibitor (negative catalyst): slows a reaction — glycerol retards the decomposition of H₂O₂.
Practice this conceptself-check · 2 quick reps
The same idea in a real exam question:
Example 1 · Surface Chemistry · Catalysis and Nanomaterials
Calling a promoter the catalyst
Concept 2 of 2: Nanomaterials and Nanocatalysts
Definition
- Surface area rises as particle size falls — hence higher catalytic activity.
- Photocatalysis: nano TiO₂ (absorbs UV and generates reactive species).
- Nano Cu and Pd clusters are harder than the bulk metal.
- Carbon nanotubes conduct electricity.
- Characterisation: SEM — structure of the material's SURFACE; XRD — crystal structure; TEM — size and shape.
Worked example
Practice this conceptself-check · 1 quick reps
The same idea in a real exam question:
Example 2 · Surface Chemistry · Catalysis and Nanomaterials
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Reference tables (1)
Watch out for (1)
- Calling a promoter the catalyst→ Homogeneous and Heterogeneous Catalysis, Promoters and Inhibitors
Test yourself on Surface Chemistry
15 past MHT-CET questions from this chapter, timed at 14 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.