# Economic importance of iron and cobalt

> From pylons to gamma rays


## Objectives

- State the uses of iron, including as a catalyst in the Haber-Bosch and Fischer-Tropsch methods.
- Describe water gas as a mixture of hydrogen and carbon monoxide.
- State the uses of cobalt and explain why cobalt 60 is used: it produces gamma rays with high penetrating power.

## 1. Economic importance of the first transition series




## 2. Iron and cobalt

Predict: why is cobalt 60 useful in treating tumours?

- It can be magnetized
- It is a very hard metal
- It produces gamma rays with high penetrating power ✓

Cobalt 60 is a radioactive isotope of cobalt that produces gamma rays with high penetrating power. That radiation is what reaches the tumour, so cobalt 60 is used in the diagnosis and treatment of tumours.

[ar-EG] الـ cobalt 60 ده radioactive isotope من الـ cobalt بيطلّع gamma rays ليها high penetrating power. الإشعاع ده هو اللي بيوصل للورم، وعشان كده الـ cobalt 60 بيتستخدم في تشخيص وعلاج الأورام.
## 3. 6- Iron in everyday life

Iron is used in the manufacture of: Uses of iron (book p.6) Look around: the steel rods inside concrete buildings are iron.


## 4. Iron as a catalyst: Haber-Bosch

Remember: a catalyst speeds up a reaction without being used up. Iron is used as a **catalyst** in the manufacture of **ammonia** by the **Haber-Bosch method**. Iron (Fe) over the arrow is the catalyst; conditions: 500 °C, 200 atm


## 5. Iron as a catalyst: Fischer-Tropsch

Water gas A mixture of hydrogen and carbon monoxide. Iron also catalyses the conversion of water gas to a fuel


## 6. Iron check

A factory passes a mixture of $\ce{H2}$ and CO over an iron catalyst. What does it make?

- Ammonia, by the Haber-Bosch method
- Water vapour
- A fuel, by the Fischer-Tropsch method ✓

A mixture of $\ce{H2}$ and CO is water gas. With iron as the catalyst it is converted to a fuel by the Fischer-Tropsch method; the Haber-Bosch method makes ammonia from $\ce{N2}$ and $\ce{H2}$.

[ar-EG] خليط الـ $\ce{H2}$ والـ CO ده هو الـ water gas. والـ iron هو الـ catalyst اللي بيحوّله لـ fuel بطريقة الـ Fischer-Tropsch؛ إنما الـ Haber-Bosch فبيعمل ammonia من الـ $\ce{N2}$ والـ $\ce{H2}$.
## 7. 7- Cobalt: magnets and batteries

Cobalt is similar to iron: both of them **can be magnetized**. So they are used in the manufacture of **magnets**. Cobalt is similar to iron: both can be magnetized (book p.7) Cobalt is also used in the manufacture of **modern dry batteries** used in cars.


## 8. Cobalt 60 and gamma rays

Cobalt has **twelve radioactive isotopes**. Cobalt 60 is very important because it produces **gamma rays** with **high penetrating power**. Uses of cobalt 60 (book p.7) Cobalt 60 is used in treating tumours because cobalt can be magnetized.


## 9. Iron or cobalt?

Mangoes are treated with gamma rays from cobalt 60 to preserve them. A buyer asks: "Are they radioactive now?" The best reply is:

- Yes, but only for a few days
- No. The rays pass through; the food does not become radioactive ✓
- No, because cobalt is magnetic

The gamma rays from cobalt 60 pass through the mangoes. The radioactive isotope stays in the source and does not get into the fruit, so the mangoes do not become radioactive.

[ar-EG] الـ gamma rays اللي بتطلع من الـ cobalt 60 بتعدّي من المانجا. الـ radioactive isotope بيفضل في المصدر ومش بيدخل الفاكهة، فالمانجا مابتبقاش radioactive.
## 10. Summary

Back to the hook: cobalt 60 treats tumours because its gamma rays have high penetrating power. Economic importance of iron and cobalt (book pp.6-7) Give reasons: cobalt 60 is used in food preserving → **it produces gamma rays which have high penetrating power**. Can you explain why gamma-treated food is not radioactive?



Chapter: Transition Elements (https://yaani.ai/en/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/en/lesson/chem-s3-en.lesson-te.uses-fe-co