Economic importance of manganese
Brittle alone, useful in alloys and compounds
1. Economic importance of the first transition series
2. Rails and cans
Train rails and soft-drink cans both contain manganese. Yet nobody makes anything from pure manganese. Why not?
Pick the right answer
Predict: what is wrong with pure manganese?
- A. It is brittle
- B. It is too soft
- C. It is too rare to use
Explanation
Pure manganese is brittle, so it is not used as a pure metal; it is used in alloys or compounds.
3. Never used pure
Brittle metal
A metal that breaks easily when it is hit or bent.
Manganese is not used as a pure metal because it is a brittle metal. So it is always used as alloys or compounds.
An alloy is a metal mixed with other elements. You'll study alloys later.
- Manganese (brittle) → Alloys
- Manganese (brittle) → Compounds
4. Two alloys
Each alloy has a use and a reason. Learn them as pairs.
| Alloy | Use | Because |
|---|---|---|
| Ferromanganese | Railway track | it is harder than steel |
Show the second alloy
| Alloy | Use | Because |
|---|---|---|
| Aluminum-manganese alloy | Soft drinks vessels (cans) | it resists corrosion |
5. Pick the alloy
Pick the right answer
Engineers need a material for a new railway track. It must be harder than steel. What fits the book?
- A. Ferromanganese alloy
- B. Pure manganese
- C. Aluminum-manganese alloy
Explanation
Ferromanganese alloy fits: the book says it is used in railway track because it is harder than steel.
True or false?
Aluminum-manganese alloys are used for soft drinks cans because they are harder than steel.
Explanation
Aluminum-manganese alloys are used for soft drinks cans because they resist corrosion. Being harder than steel is the reason ferromanganese is used in railway track.
6. Dry cell and antiseptic
MnO2
Manganese dioxide: a strong oxidizing agent used in the dry cell
KMnO4
Potassium permanganate: an antiseptic substance
Remember: an oxidizing agent oxidizes another substance.
Antiseptic
A substance that kills germs, for example on a wound.
- MnO2 → Dry cell (strong oxidizing agent)
- KMnO4 → Antiseptic (kills germs)
7. A fungicide
MnSO4
Manganese II sulphate: used as a fungicide
Fungicide
A substance that kills fungi.
| Compound | Kills | Use |
|---|---|---|
| KMnO4 | germs | antiseptic |
| MnSO4 | fungi | fungicide |
8. Match manganese uses
Sort into groups
Sort each use or reason under its alloy or compound.
Railway trackSoft drinks cansHarder than steelAntiseptic substanceFungicide
Fill in the blanks
In the dry cell, MnO2 acts as a strong _____ agent.
Explanation
MnO2 is a strong oxidizing agent used in the dry cell.
9. Summary
Back to the hook: pure manganese is brittle, so rails and cans use its alloys.
- Mn is brittle, so it is used as alloys or compounds, not as a pure metal.
- Ferromanganese: railway track. Al-Mn alloy: soft drinks cans.
- MnO2: strong oxidizing agent in the dry cell.
- KMnO4: antiseptic. MnSO4: fungicide.
Can you explain why manganese is useful, although the pure metal is brittle?
Reveal
It is used as alloys and compounds: ferromanganese in railway track (harder than steel), Al-Mn alloy in soft drinks cans (resists corrosion), MnO2 in the dry cell, KMnO4 as an antiseptic and MnSO4 as a fungicide.