Unit 2 Natures Chemistry – Section 1

Carbon Compounds

Fuels Starter:

Qu. What do the following have in common?• Oil• Paraffin• Coal• Natural gas• Wood• PeatQu. What gas is used up every time we burn a

substance?

Fire and Fuels

Question: What things do we need to put together to produce fire?

Copy the fire triangle into your notes.

Fuels

Definition:A fuel is a substance that burns to produce heat

energy. Burning is also known as combustion.Examples: • Natural Gas• Wood• Oil• Coal• Peat

Energy ReactionsIn a chemical reaction, energy can either be given out or taken in! Complete the following:

Definitions:

1. Exothermic Reactions =

2. Endothermic Reactions =

When fuels burn this is an ______________ reaction because………..

Now read, complete and paste in 2.1a

Formation of oil and gasFormation of oil and gas

1) Layers of dead sea _____ settle on the seabed.

2) Layers of _____ and rock build up on top.

3) The heat and ________ from these rocks over ________ of years turns the creatures into oil and gas.

Words – sand, millions, creatures, pressure

Formation of coal and peatFormation of coal and peat

The formation of coal and peat also took _________ of years but these ________ fuels are not made from sea creatures. They were made from _________ and plants in ancient swamps.

The coal and peat that we have in West Lothian tells us that millions of years ago this area was just one big swamp!

Words: fossil, trees, millions

Burning a Hydrocarbon Fuel

Think!

1.What two elements are in all hydrocarbons?

2. How can you prove this?

Now paste in appendix and 2.1b and 2.1c

Distillation

Starter ;

1.What do we use distillation for?

2.Think – do you think bigger molecules boil off first or last (Clue – do they have a higher boiling point)

3.Read page 6 & 7 and answer qu1-3

Crude Oil

• Crude oil is a mixture of different hydrocarbons called fractions.

• Crude oil is a source of many carbon based products including fuels like petrol, diesel, candle wax and lubricating oil as well as different chemicals used to make many other products

• These mixtures/fractions can be separated using a process called Fractional Distillation

Fractional Distillation

To do:

1. Complete the true/false Fractional distillation exercise

2. Fuels and Pollution

Create a spider diagram of ‘Fuels and Pollution’ – fill it with as many pollution issues associated with burning fuels.

(10mins)

Combustion – a Summary

• A fuel is a substance that burns in O2 to produce energy

• Combustion is another name for burning

• Oxygen gas is needed for burning to take place• A reaction which gives out energy is called an EXOTHERMIC reaction• All combustion reactions (burning) are exothermic

• Most fuels are made from compounds containing carbon and hydrogen (Hydrocarbons)

• Two types of Combustion – complete and incomplete

• Examples of fuels are petrol, coal, natural gas (methane), wood, kerosene, paraffin and diesel – what are these used for?

• By blowing on a fire we increase the oxygen concentration – so it burns with a hotter flame!

Now answer Qu1-8 on page 2 and complete appendix 2.1a

Research Task: Alternative FuelsWe know that petrol and diesel are fuels that are burned to produce energy.

Qu. What is the global environmental problem associated with burning fossil fuels like petrol and diesel?

Qu. What will eventually happen to these fossil fuels?

So what will we use to produce the energy we need to power our cars, heat our homes, supply us with electricity??

– can you suggest any alternatives?

Research Task: Using available textbooks or the internet research the following 3 alternative fuels; ethanol, hydrogen and biogas.

Success criteria; You must write about each alternative fuel detailing

i)how it is made

ii) where it is used

iii) advantages and disadvantages both in terms of being a fuel and the environment

What are Hydrocarbons?

• A hydrocarbon is a molecule which contains only the elements Carbon and Hydrogen.

• Hydrocarbons are obtained from the Fractional Distillation of crude oil.

• We use them for fuels in cars (octane) and in cookers (methane).

• Hydrocarbons exist as different ‘families’

Hydrocarbons – Homologous Series

• Definition:Homologous Series– a group of chemically similar compounds which can be

represented by a general formula. – Physical properties change gradually through the series

Now paste in

handout and

turn to page 12

of booklet.

Hydrocarbons

We will focus on the following homologous series;•Alkanes (Straight and branched chains)

•Alkenes

•Cycloalkanes

AlkanesAlkanesAlkanes are SATURATED HYDROCARBONS. HYDROCARBONS are molecules that are made up of only _________ and _________ atoms. They share a general formula. Which is…………..

SATURATED means that all of the carbon atoms are held together by ________ bonds, for example:

Ethane Butane

Alkanes are quite unreactive (but they do burn well to make __________ __________ and ______).

Starter

1. What is a homologous series?

2. Which of the following are hydrocarbons?

A. B. C.

D. E. F.

How Do We group all these alkanes together?

See page 9 of data-booklet

Aim: To learn about the first 8 alkanes; their formula, structures, properties and general formula.

Alkanes

»Methane Monsters

»Ethane Eat

»Propane Pupils

»Butane But

»Pentane Prefer

»Hexane Hairy

»Heptane Haggis

»Octane or

»Nonane Nice

»Decane Dinners

Structures: Alkanes – MethaneBuild methane using the moly mods

• 3D Full Structural 2D Full Structural

Formula Formula

Remember - Alkanes

• The Alkanes are a family of hydrocarbons and all share the same chemical properties:– Single Carbon to carbon bonds ( - C – C - )– All end in -‘ane’– Saturated hydrocarbons– All share a General Formula

Now paste in appendix 2.2 and 2.2a

Alkanes

• Each member can be represented in three different ways:

MethanePropane

• Full Structural

Formula • Shortened Structural

Formula• Molecular Formula

Alkanes

AlkaneAlkane

(Carbon (Carbon Atoms)Atoms)

Full Full Structural Structural FormulaFormula

Molecular Molecular FormulaFormula

Shortened Shortened Structural Structural FormulaFormula

Boiling Boiling

PointPoint

Methane (1)

-164

Ethane (2)

C2H6 CH3- CH3 - 89

Propane (3)

Alkanes

AlkaneAlkane

(Carbon (Carbon Atoms)Atoms)

Full Full Structural Structural FormulaFormula

Molecular Molecular FormulaFormula

Shortened Shortened Structural Structural FormulaFormula

Boiling Boiling

PointPoint

Butane (4)

Pentane (5)

Hexane(6)

Alkanes

AlkaneAlkane

(Carbon (Carbon Atoms)Atoms)

MoleculaMolecular Formular Formula

Shortened Shortened Structural Structural FormulaFormula

Full Full Structural Structural FormulaFormula

Boiling Boiling

PointPoint

HeptaneHeptane

(7)(7)

OctaneOctane

(8)(8)

Alkanes

Alkane(Carbon Atoms)

Molecular Formula

Shortened Structural Formula

Full Structural Formula

Boiling Point

Methane (1)

CH4 CH4 -164

Ethane (2)

C2H6 CH3- CH3 - 89

Propane (3)

C3H8 CH3- CH2

-

CH3 - 42

AlkanesAlkaneAlkane

(Carbon (Carbon Atoms)Atoms)

Full Structural Full Structural FormulaFormula

MoleMolecular cular FormFormulaula

Shortened Shortened Structural Structural FormulaFormula

Boiling Boiling

PointPoint

Butane (4)

C4H10 CH3-CH2

-CH2-CH3 -1

Pentane (5)

C5H12CH3

- CH2- CH2

- CH2-

CH3

36

Hexane(6)

C6H14CH3

-CH2-CH2

-CH2-

CH2-CH3

69

Alkanes

AlkaneAlkane

(Carbon (Carbon Atoms)Atoms)

MoleculaMolecular Formular Formula

Shortened Shortened Structural Structural FormulaFormula

Full Full Structural Structural FormulaFormula

Boiling Boiling

PointPoint

Heptane(7)

C7H16 CH3CH2CH2

CH2

CH2CH2CH3

98

Octane(8)

C8H18 CH3CH2CH2

CH2

CH2CH2CH3

126

Alkanes General formulaThe following hydrocarbons are members of a different

homologous series;

• For every carbon there is 2 x hydrogen minus 2 (e.g. ethyne = 2

carbons and 2 hydrogens, butyne is 4 carbons and 6 hydrogens)

Their general formula is CCnnHH2n-22n-2

Using this as a guide – work out the general fromula for the alkanes.Using this as a guide – work out the general fromula for the alkanes.

General Formula for alkanes is CGeneral Formula for alkanes is CnnHH2n+22n+2

The number of Hydrogen atoms = 2 times the number of Carbon atoms plus 2

Properties of Alkanes

• Alkanes have single carbon to carbon bonds. This makes them saturated.

• The general formula for alkanes is;

CnH2n+2

• The boiling points of alkanes increase as they get bigger

Energy from Fuels

• A fuel is a substance that burns in oxygen to produce energy.

• Different types of fuels provide different quantities of energy.

• We can measure the energy produced by a fuel when it burns experimentally.

Measuring the Energy from Fuels

Alcohols can be burned to produce energy and are regularly used in combination with other fuels to produce energy.

E.g. In Brazil alcohols can be mixed with

petrol and be used in cars!

Experiment: Calculating the Energy Released from Fuels.

The combustion of alcohols is exothermic and in this experiment the energy released from burning a known mass of alcohol is used to heat a known amount of water. From measurements taken, the quantity of energy transferred to the water can be calculated.

Now collect and paste in the Experiment handouts.

Outcome 1: Fuels InvestigationGeneral Aim: Investigate how the number of carbon atoms in a fuel affect the energy it will produce.

Using the equipment and chemicals listed on the sheet;

Plan in your groups a fair investigation method to determine how varying the number of carbons in an alcohol affect the energy released per gram of fuel.

(Remember to identify what you will change each time(your independent variable) and what you will measure each time (your dependent variable)

Check you plan with your teacher.

Variables in Investigations• An independent variable is the factor you change

in each experiment in an investigation• All other variables should be kept the same• A dependent variable is the variable being

tested/measured in a scientific experiment.

Note:The dependent variable is 'dependent' on the independent variable. As the experimenter changes the independent variable, the change in the dependent variable is observed and recorded.

Today’s PlanningAim:

Apparatus

Safety

Variables

Method – Use of equipment

- measurements to be taken

- repeated for alcohol

- repeated for different alcohols

Later: Results – Table of measurements and sample calculation for converting to 1g

Now carry out your investigation and then write it up formally (on A4 paper) including the headings;

(You must write this up yourself not in a group)

1. Aim

2. The independent variable (what you changed),

3. The dependent variable (what you measured),

4. Safety

5. The method with a diagram, mentioning all the equipment used and measurements

6. A table (with headings) of your measurements, sample calculation, and table and graph of your results (average energy)

7. Your conclusion (what you found out – must mention results and link to the aim)

8. An evaluation (Comment on how well you felt exp. Went and how you can improve your investigation)

Alkenes

• The Alkenes are a family of hydrocarbons and all share the same chemical properties:– They contain a double Carbon to carbon bonds (

- C = C - )– All end in -‘ene’– Are unsaturated hydrocarbons (due to c=c

double bond)– All share a General Formula Now paste in appendix 2.3 and 2.3a

AlkenesAlkenesAlkenes are different to alkanes; they are unsaturated.This means that they contain a _______ bond between carbon atoms.

Ethane Ethene

Butane Butene

A double bond means that alkenes can join with other molecules. This make them REACTIVE. We can tell the difference between alkenes and alkanes because alkenes decolourise bromine water but alkanes don’t.

ALK

AN

ES

ALK

EN

ES

Homologous series Homologous series A homologous series is a family of chemicals that have have the same general formula.

The alkanes are a homologous series because all members have the same _________ formula.

The alkenes are a homologous series because all members have the same __________ formula.

The first part of the name of a hydrocarbon depends on the number of carbon atoms:

meth = ___, eth= ___, ____ = 3, _____ = 4, pent = ___, ____ = ____, ____ = ____, ____= ____.

Complete #1Complete #1The name for the alkane with 5 carbon atoms is ______.

The name for the alkene with 5 carbon atoms is ______.

The name for the alkene with 12 hydrogen atoms is ________.

The name for the alkane with 18 hydrogen atoms is ________.

The name for the alkene with 3 carbon atoms is ________.

Complete #2Complete #2The molecular formula for propane is ______.

The molecular formula for hexane is ______.

The molecular formula for butane is ______.

The molecular formula for ethene is ______.

The molecular formula for octene is ______.

The molecular formula for _______ is C4H8.

The molecular formula for _______ is C7H16.

The molecular formula for _______ is C6H12.

The molecular formula for _______ is C5H12.

The molecular formula for _______ is C2H6.

Cycloalkanes

Naming Hyrocarbons

IsomersTurn to page 21 of booklet;

1. Starter: What is the definition of an isomer? Are the two compounds on the whiteboard isomers?

2. Collect and read appendix 2.6 – insert them into notes.

3. Collect a set of molymods.

Now use the molymods to complete activity 2.15(a) and 2,15(c) - name all the isomers.

Alkanols (Alcohols)Definition:• The alkanol family (sometimes known as alcohols) is a group of carbon compounds

which contain an –OH (hydroxyl) group. When attached to the molecule this is known as a functional group.

• The alkanol ethanol, is used in drinks. However, many (alkanols) alcohols are used as fuels.

• The name of all alkanols is very similar to the alkanes, as are their structures:

E.g. Methanol:

E.g. Butan-1-ol:

Now turn to page 22

and paste in appendix 2.7

Copy and complete; The AlkanolsAlkanols Molecula

r FormulaShortened Structural Formula

Full Structural Formula

Methanol

CH3 OH CH3 - OH

Ethanol

C2H5OH CH3- CH2 - OH

Propanol

CH3- CH2

- CH2 -OH

Butanol

Naming Alkanols & Isomers

• Just like the alkenes, the alkanols have isomers that are dependent on the position of the functional group, in this case the hydroxyl group (-OH).

Example; and

Draw and name the structure below!

Now complete exercise 2.3

Move onto textbook – list some uses of alkanols.

Researching Alkanols Using the internet find out about and write

a short report on;

• The chemistry of how alkanols (alcohols) are made)

• The different uses of alkanols (alcohols)

http://www.chemguide.co.uk/organicprops/alcohols/uses.html

Uses of Alcohols

• Drinks – the alcohol in beers and spirits is ethanol.

• As a fuel – ethanol can be mixed with petrol (Gasohol)

• Methylated spirits – industrial alcohol

• As a solvent – in perfumes and cosmetics

Carboxylic (Alkanoic) Acids

Carboxylic acids, sometimes known as alkanoic acids, are a homologous group of organic acids which contain the carboxyl functional group:

• The third member is;

propanoic acid• What do you think the name of the first and second members

are?

Copy and complete; The Carboxylic AcidsCarboxylic Acids

Molecular Formula

Shortened Structural Formula

Full Structural Formula

Methanoic acid

HCOOH

H-

Ethanoic acid

CH3

COOHCH3

- -

Propan__ acid

CH3- CH2

-

Butan___acid

Uses of Carboxylic Acids

• Vinegar is a solution of ethanoic acid.• Ethanoic acid can also be used as a preservative in the

food industry.• Carboxylic acids are used in household cleaning

products including soap• In manufacture of important organic compounds), acetic

anhydride (used in aspirins), cellulose acetate (used in synthetic fibres), various dyes, perfumes & medicines.

• As a solvent it dissolves phosphorus, sulphur & iodine. • Carboxylic acids can be used to make chemicals called

esters.

Researching Carboxylic Acids Using the internet find out about and write a

short report on;

The different uses of carboxylic acids (alkanoic acids)

• http://www.preservearticles.com/201101022309/uses-of-carboxylic-acids.html

EstersEsters are made by reacting a carboxylic acid with an alcohol.

Making an EsterEsters are made by reacting a carboxylic acid with an alcohol. This is known as esterification and is a CONDENSATION reaction.

The name of the ester comes from the alcohol and carboxylic acid!

Ethanoic Acid + Ethanol

O-H H

Ethyl ethanoate + Water

O-C-C-H

H

H

H

H

H-C - C

H

H O

CH3COOC2H5 H2O

Questions: 1. What is the name of the ester made by combining ethanol and propanoic acid?

2. What is the name of the alcohol and carboxylic acid which made the follow ester –Butyl propanoate

Now paste in and read Appendix 2.13

Making and naming esters

Drawing and Naming Esters

In your groups;

1.Collect an ester.

2.Write down the alcohol and acid that made it.

3.Now draw the ester.

4.Now smell the ester and complete the table on page 2

Depending on the alcohol and acid used, many different fragrances can be made.

ALCOHOL ACID Name of Ester ESTER FRAGRANCE

pentanol butanoic acid

apricot

pentanol ethanoic acid

banana

Ethanol butanoic acid

apple

ethanol ethanoic acid

fruity

Most esters have a pleasant odour and are used as perfumes and flavourings in food.