4.2 Decomposition of substances

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4.2 Decomposition of substances

After this lesson....

... I can recognize and describe decomposition.

... I can recognize and name three types of decomposition.

... I can explain the differences between combustion and decomposition. 

What is needed for a combustion?

1. Fuel and O2
2. Fuel and C
3. Fuel and H20
4. Fuel and CO2

Decomposition Reaction

1 Reactant (always a compound)

2 or more products (Can be elements or other compounds) 

Decomposition

1 reactant

2 or more products

Reactant = a compound

Combustion

2 reactants

1 or more products

Reactant = Fuel + O2

What kind of reaction is:

CuCO​3​​(s)−>CuO(s)+CO​2​​(g)

1. Combustion
2. Decomposition

Most decomposition reactions requiers energy continuously. How do we call this kind of reaction?

1. Exothermic reaction
2. Energy-effect
3. Endothermic reaction

Energy effect of decomposition reactions.

Most decomposition reactions are endothermic.

E.g. Decomposition of limstone:

Limestone(s) --> quicklime(s) + Carbon dioxide(g)

High temperatures. 

Exotherm --> warmte komt vrij

Types of decomposition reactions

Thermal decomposition

Electrolysis

Photolysis

Which substance is formed by decomposition of sugar?

In an oven is quicklime made with heating up limestone . One of the products is Carbon dioxide. What is the formula?

CaCO​3​​

1. CaO(s)−>CaCO​3​​(s)+CO​2​​
2. CaO(s)+CaCO​3​​(s)−>CO​2​​(g)
3. CaCO​3​​(s)−>CaO(s)+CO​2​​(g)
4. CaCO​3​​(s)+CO​2​​(g)−>CaO(s)

What are the 3 types of decomposition?

Sulfer chloride is seperated in sulfer and chloride with the help of the sun.

Which one?

1. Thermal decomposition
2. Electrolysis
3. Photolysis

Water is turned into hydrogen and oxygen when by electric current passing trough.

Which type of decomposition is it?

1. Thermal decomposition
2. Electrolysis
3. Photolysis

Aluminum and oxygen are formed from liquid aluminium oxide when an electric source is added.

Which one?

1. Thermal decomposition
2. Electrolysis
3. Photolysis

During the ironing of a shirt with an iron which is too hot there form scorchmarks. This is a ...

1. Thermolysis
2. Electrolysis
3. Photolysis
4. No decomposition

When you heat up glass to a really high temperature you can shape it into another form, this is ...

1. Thermolysis
2. Electrolysis
3. Photolysis
4. No decomposition

A couple of years after installation a brightly coloured curtain has become faded in colour. This happened due to ...

1. Thermolysis
2. Electrolysis
3. Photolysis
4. No decomposition

Homework

Learn blue words Chapter 4.2

Study example 1 and 2 (p.105)

Make assignments:

CM/EM: 18-22 (p.107+108)

NG/NT: 20-23 (p.107+108)

What is in your opinion the most important word of this lesson? (decomposition is not allowed)

Pick one!

Very helpful. I'v learned a lot.

Helpful, but I have to study more.

Neutral

Sorry, my internet was bad

Sorry, very tired.

Next lesson:

Marking the homework.