3TV - Chapter 4 - Section 4.1 - Combustion

• Scheikunde
• Middelbare school
• vwo
• Leerjaar 3

§4.1 Combustion

Ignition temperature!

OXYGEN

temperature

combustable substance

Ignition temperature!

OXYGEN

temperature

combustable substance

Types of combustion

With a combustion you can get different types of reaction products, dependent on the amounts of oxygen and the combustable material itself.

When there is enough oxygen you are going to get a complete combustion.

Incomplete 

combustion

Incomplete combustion

Complete 

combustion

Complete combustion of methane

Combustion products (oxides)

Element	Symbol	Name of oxide	Formula
Carbon	C	Carbondioxide
Hydrogen	H	Water
Sulphur	S	sulphurdioxide

CO​2​​

H​2​​O

SO​2​​

What are the three requirements for combustion?

1. Oxygen, gasoline and heat
2. Air, wood, lighter
3. Oxygen, fuel, temperature
4. Air, fuel, temperature

Combustion always forms:

1. Atoms
2. Fire
3. Oxides
4. Water

The combustion products of complete combustion of H2 are:

1. H2O
2. HO
3. HO2
4. CO2

The combustion products of complete combustion of  C₂H₅S are:

1. C, H, S
2. CO2, H2O, SO2
3. CO2, H2O
4. CO2, H2O, S

Combustion product in a complete combustion always contain the atom:

1. C
2. H
3. O
4. S

Reaction equations 

incomplete combustion

complete combustion

Types of combustion

With a combustion you can get different types of reaction products, dependent on the amounts of oxygen and the combustable material itself.

When there is enough oxygen you are going to get a complete combustion.

When there is a low / insufficient amount of oxygen you are going to get a partial or incomplete combustion and you will get different reaction products

Incomplete combustion 

of compound with 

C and H atoms

• Insufficient oxygen
• Yellow flame
  
• 
  
•       and             ( bit of            ) 

Complete combustion 

of compound with 

C and H atoms

• Enough oxygen
• Blue flame
•  
• 
  

H​2​​O

H​2​​O

CO​2​​

CO​2​​

CO

C

How to extinguishing a fire

You now know which three factors are necessary the get a fire started.
If you want to extinguish a fire, you must remove one (or more) of these factors.

For each situation, you can examine which factor is easiest to remove and therefor determine which extinguishing method can be used.

For example, in the event of a fire caused by a gas leak, it is wise to first close the gas tap (remove fuel).

Look at the sentences below about extinguishing a fire.

Drag the sentences to the side of the triangle that you have to remove.

Close the gas tap.

Extinguish a paper fire with water

Wrapping someone in a fire blanket.

Blow out a lighter.

Place the lid on the deep fryer.

Extinguish a gasoline fire with foam

A reagent is a substance that reacts in a characteristic, observable manner (sound or color) with the substance you want to demonstrate.

A reagent needs two meet two requirements:

Selective: the reagent only reacts to one (or little) substance(s)

Sensitive: little amount is required of both the reagent as 
                    the substance to be detected. 

There are some reagents you need to know about.

Reagent (plural: reagents)

Copy this scheme in your chemistry notes 

show	reagent/method	Observation
water
	limewater
sulfur dioxide
	glowing splint
	flame	you hear a characteristic 'pop'

You must complete this table with the help of the following slides.

Demo - Reagents

Reagent for water

Reagent for carbondioxide

Watch the above (Dutch) videos to complete your table further. Good luck.

Practise makes perfect.

Your table should be completely filled in.

Answer the following questions to see if your knowledge about reagents is complete enough. 

Improve your schedule if necessary.

White copper sulphate is a ... to demonstrate the presence of ... .

1. reagent, carbon dioxide
2. reagent, hydrogen
3. reagent, water
4. reagent, oxygen

A reagent that detects only one or very few different substances is called ....

1. sensitive
2. sensible
3. selective
4. obvious

Which statements are true?
1) A reagent must be sensitive and therefore must react
with a little bit of the substance
2) A reagent must be selective and therefore it must only react
with itself

1. A and B are true
2. A is true, B is not true
3. A is not true, B is true
4. A and B are not true

The presence of oxygen can be shown by:

1. collect the gas in a test tube and hold the opening near a flame you hear a 'pop'
2. collect the gas in a test tube and hold a glowing splint in the test tube, the splint will glow brighter

The 'pop' that you hear is evidence of the presence of

1. carbon dioxide
2. hydrogen
3. oxygen
4. water

The flask contains lime water. A second substance is sucked through the lime water. Which substance can you detect with lime water?

1. Water
2. Carbon dioxide
3. Oxygen
4. None of the three options

You can show the presence of carbon dioxide with lime water. What happens to the limewater when it reacts with carbon dioxide?

1. It's going to solidify
2. It becomes yellow and cloudy
3. It becomes a clear liquid
4. It becomes cloudy white

What is the reagent of SO2?

1. iodine solution
2. white copper sulphate
3. lime water
4. starch

Which reagent is used to demonstrate:

oxygen

carbon dioxide

water

hydrogen

sulfur dioxide

clear lime water

white copper sulphate 

glowing splint

flame

iodine solution

What observation do you do when demonstrating:

oxygen

carbon dioxide

water

hydrogen

sulfur dioxide

clear colorless liquid turns white cloudy

white solid becomes a blue solid

will glow brighter

flame

clear yellow liquid becomes clear colorless liquid

Overview of                                              

Reagents:            * Carbondioxide

                * Water

                                * Sulfurdioxide

                  * Starch

colourless Limewater
(becomes turbid)

White copper(II) sulfate
(white becomes blue)
Custard (white becomes yellow)

Iodine solution (brownyellow, becomes colourless)

Iodine solution
(brownyellow, becomes purple)

What is incomplete combustion?
A combustion with ........
oxygen

1. too much
2. insufficient
3. no
4. enough

What color becomes a flame with incomplete combustion?

1. yellow
2. blue

Has there been complete combustion?

1. yes
2. no

What type of reaction is this?

2C​8​​H​18​​+25O​2​​−>16CO​2​​+18H​2​​O

1. Seperation
2. Complete combustion
3. Decomposition reaction
4. Incomplete combustion

Ethanol + oxygen --> carbondioxide + carbon + water

This reaction is ...

1. Complete combustion
2. Incomplete combustion
3. No combustion