What is the topic for today?

FuelsCombustion and

Incomplete Combustion

Learning Objectives:1.Know word (and symbol) equations for complete combustion and the limewater test for CO2. 2.Describe the differences between complete and incomplete combustion.3.Write word equation for complete and incomplete combustion.

When a substance burns, it is said to combust.

A fuel is a substance that reacts with oxygen (combusts) to release useful energy.

1. Combustion, fuels and hydrocarbons

Many fractions obtained from crude oil are used as fuels because they contain hydrocarbons that burn easily and release a large amount of useful energy.

Combustion is a rapid reaction between a substance and oxygen that releases heat and light energy.

What are the products of the complete combustion of a hydrocarbon?

If a flame has A LOT of oxygen, the fuel will burn completely.

oxygencarbon dioxide

hydrocarbon + + water

Complete combustion of a hydrocarbon (in this case, natural gas) releases the most energy (hottest flame).

2. Complete combustion of hydrocarbons

3. Oxidation

• Combustion is a form of oxidation.

• Oxidation is a chemical reaction where oxygen is added.

4. Complete combustion of propane

Propane is a hydrocarbon used in camping gas. What is the equation for its combustion?

oxygencarbon dioxide

propane + + water

O2 CO2C3H8 + + H2O

Write the word and symbol equation for the burning of

a) methane b) ethane c) butane

5O2 3CO2C3H8 + + 4H2O

Extra Challenge:

Balance it!

5. Test for CO2

• What is the test for CO2?

• Bubble the gas through limewater. Limewater turns cloudy in the presence of CO2.

If there is a shortage of air (oxygen), incomplete combustion of hydrocarbons takes place.

Instead of producing just carbon dioxide and water, incomplete combustion also produces carbon monoxide and/or carbon (soot).

It also releases less energy than complete combustion.

6. Incomplete combustion of hydrocarbons

What is the chemical equation for incomplete combustion?

7. Word equation

hydrocarbon + oxygen

carbon dioxide + carbon monoxide + carbon + water

8. Pollution

• Combustion causes pollution.

• Pollutant: a substance which causes harm to organisms or the environment.

• Pollutants from combustion:a) Carbon dioxide

b) Carbon monoxide

c) Carbon soot

d) Sulfur dioxide

e) Nitrogen oxides

9. Global Warming

• Watch the video and answer the following questions.

• What is global warming?

• What causes it?

• Describe the greenhouse effect.

• Global warming is the increasing of the average worldwide temperature.

• It is caused by greenhouse gases such as carbon dioxide, methane, and water vapour.

• The greenhouse effect is the heating of the earth caused by greenhouse gases trapping heat from the sun near the earth’s surface.

10. Acid rain

• Acid rain is rain that has a lower pH than normal (lower than 5.5)

• Acid rain is caused by pollutants such as sulphur dioxide and nitrogen oxides from combustion of fuels.

Effects

a)Organisms in lakes can die

b)Trees are damaged

c)Buildings/rocks are corroded

11. Pollutants Summary

Pollutant Cause Effect

Carbon dioxide All combustion Global warming, makes ocean more acidic

Carbon monoxide

Incomplete combustion

Poisonous, reduces blood’s ability to carry oxygen

Carbon (soot) Incomplete combustion

Breathing problemsGlobal dimming

Sulphur dioxide Combustion of fossil fuels with sulphur impurities

Acid rain (sulphuric acid) and breathing problems

Nitrogen oxides Combustion of fuels inside car engines

Acid rain (nitric acid)