# Catalyst

> Faster reactions, nothing used up


## Objectives

- Define a catalyst: it speeds up a chemical reaction without being used up.
- Show that the catalyst is written over the arrow in an equation.
- Explain that the catalyst is recovered unchanged and does not make more product.

## 1. Magnetic properties and catalytic activity




## 2. The fizzing powder

Predict: what happens to the manganese dioxide?

- It turns into the oxygen gas
- It is used up, little by little
- It is still there at the end, with the same mass ✓

Manganese dioxide is a catalyst: it speeds up the release of oxygen from hydrogen peroxide and is still there at the end, with the same mass. Filtering, drying and weighing it shows this.

[ar-EG] الـ manganese dioxide ده catalyst: بيسرّع طلوع الـ oxygen من الـ hydrogen peroxide، وبيفضل موجود في الآخر بنفس الكتلة. ولو فلترناه ونشّفناه ووزنّاه هنشوف ده.
## 3. What a catalyst is

Catalyst A substance that speeds up a chemical reaction without being used up or changed. Manganese dioxide is written over the arrow The catalyst is written **over the arrow**. It is not a reactant, and it is not a product.


## 4. Same mass at the end

The catalyst is recovered unchanged The catalyst is consumed in the reaction.


## 5. Try a new reaction

Oxygen is also made from potassium chlorate: $\ce{2KClO3 ->[MnO2][\Delta] 2KCl + 3O2}$. What happens to the $\ce{MnO2}$?

- It is used up to make the oxygen
- It speeds up the reaction and is recovered unchanged ✓
- It turns into potassium chloride

$\ce{MnO2}$ is written over the arrow, so it is the catalyst: it speeds up the reaction and is recovered unchanged. The oxygen and the KCl both come from $\ce{KClO3}$.

[ar-EG] الـ $\ce{MnO2}$ مكتوب فوق السهم، يبقى هو الـ catalyst: بيسرّع الـ reaction وبيرجع زي ما هو من غير تغيير. والـ oxygen والـ KCl الاتنين جايين من الـ $\ce{KClO3}$.
## 6. Summary

A catalyst speeds up a chemical reaction without being used up. It is written over the arrow, for example $\ce{MnO2}$ in making oxygen from $\ce{H2O2}$. It is recovered with the same mass and gives no extra product. Back to the hook: the black powder is still there, with the same mass. In Chapter 1: transition elements as catalysts in industry. Can you explain how weighing shows that $\ce{MnO2}$ is a catalyst? Weigh the $\ce{MnO2}$, add it to $\ce{H2O2}$, then filter, dry and weigh it again: it has the same mass as at the start. It was not used up, yet oxygen bubbled out fast, so it is a catalyst.



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