# Nickel, iron and V₂O₅ as catalysts

> Which catalyst for which process


## Objectives

- Pair finely divided Ni with the hydrogenation of oils and Fe with the Haber-Bosch method.
- Pair V₂O₅ with the contact method and MnO₂ with the decomposition of H₂O₂.
- Write the Haber-Bosch and contact-method equations with the catalyst and conditions over the arrow.
- Explain why the nickel catalyst is finely divided.

## 1. Magnetic properties and catalytic activity




## 2. One catalyst for all?

Predict: can all three use the same catalyst?

- No: each process has its own catalyst ✓
- No catalyst is needed if the factory heats enough
- Yes: any transition element speeds up any reaction

Each process has its own catalyst: finely divided nickel for the hydrogenation of oils, iron for ammonia (Haber-Bosch method) and $\ce{V2O5}$ for the first step towards sulphuric acid (contact method). Heating alone does not replace the catalyst the book names for each process.

[ar-EG] كل عملية ليها الـ catalyst بتاعها: الـ finely divided nickel للـ hydrogenation of oils، والـ iron للـ ammonia (الـ Haber-Bosch method)، والـ $\ce{V2O5}$ لأول خطوة في طريق الـ sulphuric acid (الـ contact method). والتسخين لوحده مش بيغني عن الـ catalyst اللي الكتاب حدده لكل عملية.
## 3. Nickel: hydrogenation

Hydrogenation Adding hydrogen to a substance; here, to oils. **Finely divided nickel** is used as a catalyst in the hydrogenation of oils. It turns liquid oils into solid fats. Hydrogenation of oils Finely divided means a very fine powder. A powder has a huge surface, so many surface atoms meet the molecules.


## 4. Iron: Haber-Bosch

Divided iron is used as a catalyst in the preparation of ammonia gas by the **Haber-Bosch method**. Book p.15 Iron is also the catalyst in the Fischer-Tropsch method, which turns water gas into a fuel (from iron's uses).


## 5. V₂O₅: contact method

Contact method The industrial preparation of sulphuric acid. Vanadium pentoxide, $\ce{V2O5}$, is used as a catalyst in the first step: Then sulphur trioxide and water give sulphuric acid.


## 6. Match the catalyst

Add one you know from fig 1-3: $\ce{MnO2}$ in the decomposition of $\ce{H2O2}$. Which catalyst does each reaction or process use?


## 7. Spot the error

Which is the correct way to write the first step of the contact method? A student writes $\ce{N2 + 3H2 ->[V2O5] 2NH3}$. What is wrong?


## 8. Conditions from memory

In the Haber-Bosch method the catalyst is ___, at 500 °C and ___ atm. In the contact method the catalyst is ___, at ___ °C.


## 9. Summary

Finely divided Ni: hydrogenation of oils. Fe: Haber-Bosch (500 °C / 200 atm); also Fischer-Tropsch. $\ce{V2O5}$: contact method (450 °C). $\ce{MnO2}$: decomposition of $\ce{H2O2}$. Each process has its own catalyst. Exam tip: catalysts in equations Write the catalyst and the conditions **over the arrow**, never as a reactant. Fe goes with ammonia; $\ce{V2O5}$ goes with sulphuric acid. Back to the hook: each process has its own catalyst. Can you explain why the nickel is used as a fine powder?



Chapter: Transition Elements (https://yaani.ai/ar/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/ar/lesson/chem-s3-en.lesson-te.catalysis-examples