# Economic importance of copper and zinc

> Ancient bronze, modern cables and galvanized iron


## Objectives

- State the uses of copper: bronze (copper-tin alloys), electric cables and coins.
- State the uses of copper II sulphate and Fehling's solution (detecting glucose: blue to orange).
- State the uses of zinc (galvanizing) and its compounds ZnO and ZnS.

## 1. Economic importance of the first transition series




## 2. The first metal

Predict: bronze is an alloy (a metal mixed with other elements) of copper and…

- zinc
- iron
- tin ✓

Bronze is an alloy of copper and tin: the book says copper-tin alloys are known as bronze.

[ar-EG] الـ bronze هو alloy من الـ copper والـ tin: الكتاب بيقول إن الـ alloys اللي من copper و tin اسمها bronze.
## 3. 9- Copper

Copper is the **first discovered metal**. Copper-tin alloys are known as **bronze**. Copper is a **good conductor of electricity**, so it is used in **electric cables** and the **coins industry**. Copper uses (book p.7) Bronze is copper + zinc.


## 4. Fehling's solution

**Fehling's solution** is one of the copper compounds. It is used to detect **glucose**. Slide to add glucose and heat. Glucose added (0 = no, 1 = yes) No glucose: it stays blue Glucose: the blue colour changes to orange


## 5. Read the test

A student tests a sugar-free drink with Fehling's solution and heats it. It stays blue. What does that show?

- The drink contains copper
- No glucose was detected ✓
- Glucose is present

The test detected no glucose. Fehling's solution starts blue, and glucose changes the blue colour to orange; a solution that stays blue shows no glucose.

[ar-EG] مفيش glucose اتكشف. الـ Fehling's solution لونه أزرق من الأول، والـ glucose هو اللي بيغيّر الأزرق لبرتقاني؛ فلما الـ solution يفضل أزرق يبقى مفيش glucose ظهر.
## 6. 10- Zinc: galvanizing

Remember: iron rusts in moist air. Galvanizing Coating other metals with zinc to protect them from rusting. Zinc is used in **galvanizing other metals** to protect them from rusting. Think of the grey iron sheets on many rooftops. Galvanizing


## 7. Copper and zinc compounds

Compounds of copper and zinc (book pp.7-8) Remember: X-rays are invisible. A ZnS screen glows where they hit it, so we can see the picture. O or S? Zinc **oxide**: paints, rubber, cosmetics. Zinc **sulphide**: things that glow.


## 8. Copper or zinc?

Sort each use under the metal or its compounds. Bronze is an alloy of copper and ___.


## 9. Summary

Back to the hook: ancient bronze is copper + tin. Cu: the first discovered metal; bronze = copper-tin alloys; cables and coins (good conductor). $\ce{CuSO4}$: insecticide, fungicide, water purification. Fehling's: blue to orange with glucose. Zn: galvanizing other metals against rust. ZnO: paints, rubber, cosmetics. ZnS: illuminating paints and X-ray screens. Key words: **bronze = copper + tin**, **good conductor of electricity**, **blue changes to orange**, **galvanizing**. Can you explain why a Fehling's test that stays blue means no glucose? Fehling's solution starts blue, and glucose changes the blue colour to orange. If it stays blue, the colour did not change, so no glucose was detected.



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-cu-zn