# Economic importance of manganese

> Brittle alone, useful in alloys and compounds


## Objectives

- Explain why manganese is not used as a pure metal.
- Give the uses of ferromanganese (railway track) and aluminum-manganese alloys (soft drinks cans), with the reasons.
- State the uses of $\ce{MnO2}$ (dry cell), $\ce{KMnO4}$ (antiseptic) and $\ce{MnSO4}$ (fungicide).

## 1. Economic importance of the first transition series




## 2. Rails and cans

Predict: what is wrong with pure manganese?

- It is too soft
- It is too rare to use
- It is brittle ✓

Pure manganese is brittle, so it is not used as a pure metal; it is used in alloys or compounds.

[ar-EG] الـ manganese النقي هش (brittle)، عشان كده مش بيُستخدم كـ metal نقي، وبيُستخدم في alloys أو 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. How manganese is used


## 4. Two alloys

Each alloy has a use and a reason. Learn them as pairs. Alloy 1 (book p.6) Show the second alloy Alloy 2 (book p.6)


## 5. Pick the alloy

Engineers need a material for a new railway track. It must be harder than steel. What fits the book?

- Pure manganese
- Aluminum-manganese alloy
- Ferromanganese alloy ✓

Ferromanganese alloy fits: the book says it is used in railway track because it is harder than steel.

[ar-EG] الـ ferromanganese alloy هو اللي ينفع: الكتاب بيقول إنه بيُستخدم في قضبان السكة الحديد عشان أصلد من الـ steel.
## 6. Dry cell and antiseptic

$\ce{MnO2}$ Manganese dioxide: a strong oxidizing agent used in the dry cell $\ce{KMnO4}$ Potassium permanganate: an antiseptic substance Remember: an oxidizing agent oxidizes another substance. Antiseptic A substance that kills germs, for example on a wound. Two manganese compounds and their uses


## 7. A fungicide

$\ce{MnSO4}$ Manganese II sulphate: used as a fungicide Fungicide A substance that kills fungi. $\ce{MnSO4}$ is the antiseptic and $\ce{KMnO4}$ is the fungicide. Do not swap them


## 8. Match manganese uses

Sort each use or reason under its alloy or compound. In the dry cell, $\ce{MnO2}$ acts as a strong ___ agent.


## 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. $\ce{MnO2}$: strong oxidizing agent in the dry cell. $\ce{KMnO4}$: antiseptic. $\ce{MnSO4}$: fungicide. Give reasons: Mn is not used pure → **it is a brittle metal**. Ferromanganese in rails → **harder than steel**. Al-Mn cans → **resists corrosion**. Can you explain why manganese is useful, although the pure metal is brittle? It is used as alloys and compounds: ferromanganese in railway track (harder than steel), Al-Mn alloy in soft drinks cans (resists corrosion), $\ce{MnO2}$ in the dry cell, $\ce{KMnO4}$ as an antiseptic and $\ce{MnSO4}$ as a fungicide.



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