# Economic importance of vanadium and chromium

> Hard springs, a busy oxide and a strong oxidizing agent


## Objectives

- Explain why a small portion of vanadium is added to steel for car springs.
- State the uses of vanadium pentoxide ($\ce{V2O5}$): dyes in ceramics and glass, a catalyst, strong magnetic conductors.
- State the uses of chromium (metal plating, leather tanning) and its compounds ($\ce{Cr2O3}$ for dyes, $\ce{K2Cr2O7}$ as an oxidizing agent).

## 1. Economic importance of the first transition series




## 2. Springs that last

Predict: the steel of car springs contains vanadium. How much?

- About half of the spring is vanadium
- A small portion added to the steel ✓
- The spring is made of pure vanadium

A small portion of vanadium is added to the steel. It forms an alloy of high hardness that resists corrosion, so it is used to make car springs.

[ar-EG] بيتضاف جزء صغير من الـ vanadium للـ steel. ده بيكوّن alloy صلادته عالية وبيقاوم الـ corrosion، عشان كده بيُستخدم في صناعة الـ car springs.
## 3. 3- Vanadium in steel

Remember: corrosion slowly eats a metal away in air and moisture. When we add **a small portion of vanadium to steel**, an alloy of **high hardness** forms. It has a **great ability to resist corrosion**. So it is used in the manufacture of **car springs**. An **alloy** is a metal mixed with other elements. You'll study alloys later. Vanadium steel (book p.6)


## 4. Vanadium pentoxide (V₂O₅)

Vanadium pentoxide: an important compound of vanadium Dyes In the manufacture of ceramics and the glass industry Catalyst Speeds up a reaction without being used up Magnetic conductors In the manufacture of strong magnetic conductors $\ce{V2O5}$ is just a dye.


## 5. Vanadium check

Which of these are uses of vanadium pentoxide ($\ce{V2O5}$)? Choose all that apply.


## 6. 4- Chromium and its compounds

Chromium is a **chemically active metal**, but it resists the effect of atmospheric air. Chromium is used in **metal plating** and **leather tanning**. Chromium and its important compounds (book p.6) Why does an active metal resist air? A later lesson explains it.


## 7. An oxidizing agent

Remember: an **oxidizing agent** oxidizes another substance. It is itself reduced. Potassium dichromate, $\ce{K2Cr2O7}$, is used as an **oxidizing agent**. It makes other substances undergo oxidation. Oxidizing agent vs reducing agent $\ce{K2Cr2O7}$ is a reducing agent.


## 8. Vanadium or chromium?

A lab adds potassium dichromate to a reaction mixture. What is its job?

- It oxidizes another substance, and is itself reduced ✓
- It takes oxygen away from another substance
- It colours the mixture as a dye
- It speeds up the reaction and is not used up

Potassium dichromate ($\ce{K2Cr2O7}$) is used as an oxidizing agent: it oxidizes another substance and is itself reduced.

[ar-EG] الـ potassium dichromate ($\ce{K2Cr2O7}$) بيُستخدم كـ oxidizing agent: يعني بيأكسد مادة تانية وهو نفسه بيتختزل.
## 9. Summary

Back to the springs: a small portion of vanadium makes steel very hard and corrosion resistant. V in steel: high hardness alloy, resists corrosion: car springs. $\ce{V2O5}$: dyes in ceramics and glass, a catalyst, strong magnetic conductors. Cr: metal plating and leather tanning. $\ce{Cr2O3}$: dyes. $\ce{K2Cr2O7}$: an oxidizing agent. Key words: **a small portion**, **high hardness**, **resist corrosion**, **catalyst**, **oxidizing agent**. Can you explain why $\ce{V2O5}$ is more than just a dye? Besides dyes for ceramics and glass, $\ce{V2O5}$ is an important **catalyst** (it speeds up a reaction and is not used up) and is used in the manufacture of **strong magnetic conductors**.



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-v-cr