L03. Burning hydrocarbons

Lesson OutcomesAPP AF1, AF2, AF3, AF4

HSW 1a, 2c

How I did Targets

Task 1: Describe what happens when hydrocarbon fuels burn, and how the products of combustion can be identified.

Grade C

Task 2:Explain: • the advantages of complete combustion

and link this to the choice of fuels.• The problems associated with incomplete

combustion

Grade B

Task 3: Write balanced symbol equations for complete, and incomplete, combustion

Grade A/A*

Connector: (Grade D)Answer in full sentences1. What is a fuel?2. Name three fuels.3. What do you consider to be the most important properties of a fuel?4. What is the scientific word for when a fuel burns?

1. A fuel is a substance that contains stored chemical energy.

When fuels are burned in the air (with oxygen) they release heat and light energy.

2. petrol, wood, ethanol, coal, macaroni, sugar, etc.

3. A good fuel would release a lot of heat energy with little or no polluting or harmful by-products.

4. Combustion

BIG picture

• What skills will you be developing this lesson?

• ICT• Numeracy• Literacy• Team work• Self management• Creative thinking• Independent enquiry • Participation• Reflection

• How is this lesson relevant to every day life? (WRL/CIT)

Task 1 (Grade C)

• Task 1: Describe what happens when hydrocarbon fuels burn, and how the products of combustion can be identified.

Keywords for Task 1:

Combustion, Complete combustion Fuel

Combustion

fuel

Compounds containing H and

C are called?

Many fuels like coal, oil, petrol, candle wax, and natural gas are called HYDROCARBONS

The products of burning a hydrocarbon

water and ice

water and ice

anhydrous cobalt chloride paper

limewater

Hydrocarbons are compounds of carbon and hydrogen ONLY.When pure carbon is burned, carbon dioxide is formed and when hydrogen is burned, water is produced.

to pump

1. What happens to the anhydrous cobalt chloride paper?2. What happens to the limewater?3. Explain the significance of the above observations.

Task 1: Review

Lesson Outcomes How I did Targets

Task 1:

Describe what happens when hydrocarbon fuels burn, and how the products of combustion can be identified.

Grade C

Met?

Partly met?

Not met?

How can I improve on task 1?

Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

Task 2 (Grade B)

• Task 2: Explain:

– the advantages of complete combustion and link this to the choice of fuels.

– The problems associated with incomplete combustion

• Task 2: Extension

Keywords for Task 2:

• Combustion, • Complete combustion, • Fuel• Carbon monoxide,• Incomplete combustion,• Pollution,• Soot,• Toxicity

What makes a good fuel?What makes a good fuel?

Yellow flame, soot Blue flame, no soot Yellow flame, soot, ash (residue)

From the pictures below, choose the best fuel. Explain your choice.

Summary exercise

• Fuels contain stored __________ . When fuels burn they react with __________ in the air and give out __________ energy. This is called a __________ reaction. Most fuels contain carbon and __________ atoms. When the fuel burns these atoms react with oxygen to make __________ dioxide and __________ .

carbon combustion energy heathydrogen oxygen water

energy

oxygen

heat

combustion

hydrogen

carbon water

Lots of oxygen:

Some oxygen:

Little oxygen:

Methane Oxygen+

Water+

Carbon dioxide

Carbon monoxide

Carbon

(soot)

Methane Oxygen+

Water+

Methane Oxygen+ Water+

Complete and incomplete combustion

This is called Complete combustion

This is called Incomplete combustion

This is also called Incomplete combustion

To get complete combustion the fuel must be burned in EXCESS O2.

Why did the man die?

Less amount of available oxygen caused the release of colourless, odourless, poisonous carbon monoxide.

The hazard of incomplete combustion

Incomplete combustion

Carbon monoxide

Edexcel video

Question

Homework

• Homework task:

• Due date:

• Criteria for Grade C:

• Criteria for Grade B

Summary

• When a fuel burns with a good supply of __________ to form carbon dioxide and water it is called __________ combustion. When a fuel burns without a good enough supply of oxygen and forms deadly carbon __________ (and/or soot) and water it is called __________ combustion. Incomplete combustion can happen in faulty gas boilers if their air __________ vent is blocked. Carbon monoxide is a __________ , __________ , toxic gas. It kills because it stops your blood from carrying __________ .

colourless complete incomplete intakemonoxide odourless oxygen oxygen

oxygen

incomplete

monoxide

complete

intake

odourless colourless

oxygen

Task 2: Review

Lesson Outcomes How I did TargetsTask 2:

Explain: • the advantages of complete

combustion and link this to the choice of fuels.

• The problems associated with incomplete combustion

Grade B

Met?

Partly met?

Not met?

How can I improve on task 2?

Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

Task 3: (Grade A/A*)

• Task 3:

Write balanced symbol equations for complete, and incomplete, combustion

• Task 3: Extension

Keywords for Task 3:

• incomplete combustion

• complete combustion

Combustion of methaneCombustion of methane

1. Write the word equation for combustion of methane.2. Write a balanced symbol equation for the combustion of methane.

+

Write the balanced symbol equations for these reactions: Write the balanced symbol equations for these reactions:

Extension task• Some camping gas stoves run on propane gas. Propane

molecules have the formula C3H8.

• (a) What new chemicals are produced when you burn propane?

• (b) Write a word equation for the combustion reaction of propane.

• (c) Write a balanced formula equation for this reaction. (Hint: you will need five oxygen molecules for every propane molecule.)

Task 3: Review

Lesson Outcomes How I did Targets

Task 3:

Write balanced symbol equations for complete, and incomplete, combustion

Grade A/A*

Met?

Partly met?

Not met?

How can I improve on task 3?

Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

Review of lesson – a selection of past paper questions

Question

Combustion,

complete combustion,

Fuel

Carbon monoxide,

incomplete combustion,

pollution,

soot,

toxicity

Can you explain these key words?

Technicians’ list

Demonstration 1Eye protectionTwo gas jars of oxygenDeflagrating spoonTwo stoppered boiling tubes of hydrogenDry cobalt chloride paper (blue)ForcepsSplintsLimewater (corrosive)Charcoal

Demonstration 2Combustion rig