21) a) Fuels and heats of reaction

Organic chemistry

Is the study of compounds of carbon

Hydrocarbons

Compounds consisting of hydrogen and carbon only, bonded together covalently

Sources of hydrocarbons

Fossil fuels such as

- crude oil

- natural gas

- coal

What is crude oil formed from

The remains of marine plants and animals (mainly plankton)

What is coal produced from

Produced from dead wood

Where is methane produced

- coal mines

- slurry pits

- waste tracts

- digestive tracts of animals

What effect does methane have on the environment

Worse than CO2 for global warming as it traps greater heat - there is less of it

Hazards of methane

1. Fires and explosions

2. Death by suffocation (slurry pits)

3. Contributes to the greenhouse effect

Aliphatic hydrocarbons

Hydrocarbons that consist of straight or branched chains of carbon atoms, or rings of carbon atoms other than those containing a special ring called benzene

3 examples of aliphatic hydrocarbons

- pentane - a straight chain aliphatic hydrocarbon

- a branched chain hydrocarbon

- cyclohexane - a cyclic aliphatic hydrocarbon (non-polar solvent)

Homologous series

- a series of compounds of similar chemical properties

- showing graduations in physical properties

- having a general formula for its members

- each member having a similar method of preparation

- each member differing by a CH2 unit

Systemic prefixes for homologous compounds

1. Meth

2. Eth

3. Prop

4. But

5. Pent

6. Hex

7. Hept

8. Oct

9. Non

10. Dec

3 homologous series of aliphatic hydrocarbons

alkanes, alkenes, alkynes

Alkanes

Alkanes are a homologous series of hydrocarbons with the general formula CnH2n+2

They are named systemically with a prefix indicating the number of carbon atoms per molecule, and the ending —ane

Are alkanes saturated or unsaturated?

saturated

What is a saturated compound

One in which there are only single bonds between the atoms in the molecule

Name the alkanes 1 - 10 with formula

1. Methane - CH4

2. Ethane - C2H6

3. Propane - C3H8

4. Butane - C4H10

5. Pentane - C5H12

6. Hexane - C6H14

7. Heptane - C7H16

8. Octane - C8H18

9. Nonane - C9H20

10. Decane - C10H22

What shape are alkane molecules

tetrahedral

Example - propane

What shape does any single bond of carbon take

Tetrahedral

Structural formula

The structural formula of an alkane indicates the way atoms in a molecule of the alkane are bonded together

Be able to draw alkanes methane - decane

*every carbon must have four lines/four electrons shared (unless ion)

*carbons connect to other carbon in branched chains

Structural isomers

Compounds that have the same molecular formula but different structural formulas

Which is the simplest alkane with structural isomers

Butane (C4H10)

- butane

- 2 - methylpropane - indicates that there is a methyl (CH3) group attached instead of one of the hydrogen atoms to the second carbon in propane

Structural isomers of butane

- butane

- 2 - methylpropane - indicates that there is a methyl (CH3) group attached instead of one of the hydrogen atoms to the second carbon in propane

Isomer of octane

2,2,4 - trimethylpentane is called so because there are 2 methyl groups attached (in the place of hydrogen atoms) to the second carbon atom, and one (in place of another hydrogen atom) to the fourth carbon atom in pentane molecule

Physical properties of alkanes

- physical state - the first four alkanes are gases, while pentane and higher are liquids

(boiling point increases with increasing number of carbons - this is because the molecular mass increases which leads to more electrons. This gives stronger intermolecular forces (van der waals forces))

- insoluble in water

- soluble in non-polar solvents like cyclohexane

(Like dissolves like - non polar molecules dissolve polar molecules)

General formula of alkenes

CnH2n

Are alkenes saturated or unsaturated? Why?

-Unsaturated because they have a C=C double bond

Unsaturated compound

one which contains one or more double or triple bonds between the atoms in the molecule

Alkenes to know and draw

First 4

(No methene) - need 2 carbons for a carbon double bond)

1. Ethene

2. Propene

3. But - 1 - ene

4. But - 2 - ene

5. Cyclohexene

What shape are single bonds between carbon atoms (???)

Tetrahedral

What shape are double bonds between between carbon atoms

Trigonal planar - any carbon attached to a double bond exists on one plane

what shape is ethene

trigonal planar

Physical properties of alkenes

1. Gases - first 3

2. Insoluble in water - alkenes are non polar and will not dissolve in polar solvents like water as like dissolves like

3. Soluble in non polar solvents like cyclohexane

Uses of ethene

- can be used in the food industry to speed the ripening of fruit during storage and transport

- starting material for many other substances - plastics

General formula of alkynes

CnH2n-2

Are alkynes saturated or unsaturated?

unsaturated

What do alkynes contain

carbon-carbon triple bond

Which member of alkynes do you need to know

Ethyne - C2H2

Be able to draw ethyne

H - C -(TRIPLE) - C - H

Uses of ethyne

For welding and cutting metals

Physical properties of ethyne

- physical state - gas

- insoluble in water

- soluble in non polar solvents such as cyclohexane

What are aromatic hydrocarbons

What is an aliphatic compound?

An organic compound that consists of open chains of carbon atoms and closed chain compounds (rings) that resemble them in chemical properties

What do unsaturated hydrocarbons have

A double or triple bond ex. Propene/ethyne

What is the most important aromatic hydrocarbon

benzene - C6H6

formula of benzene

C6H6

What are aromatic compounds

compounds which contain a benzene ring structure in their molecules

be able to draw the 3 structures of benzene

Hexagon with 3 lines, hexagon with circle, like cyclohexane but with 3 lines

Quizlets description oft the structure of benzene

- A cyclic planar molecule with formula C₆H₆

- Each carbon bonds to two other carbons and one hydrogen.

- Each of the carbon has a lone electron in the P orbital which sticks out above and below the planar ring.

- The lone electrons in the P-orbital combine to form a ring of delocalised electrons

Structure of benzene

- six carbon atoms joined to form a hexagonal planar ring

- each of these carbons has four valence electrons

- one of these is used to form a bond with a hydrogen atom

- two other electrons are used to form sigma bonds with the carbon atoms on the either side

Unusual properties of benzene

- benzene should be highly reactive as it is an unsaturated molecule, however it isn't

- carbon-carbon bonds are of equal length between a single and double bond

- reason it is not highly reactive - due to the 6 valence electrons being shared between the 6 carbon atoms and not localised into 3 double bonds. These are known as delocalised electrons

What special bonds does benzene have

Delocalised pi bond

3 main aromatic hydrocarbons

1. Benzene (C6H6)

2. Methylbenzene (C6H8)

3. Ethylbenzene (C8H10)

BE ABLE TO DRAW STRUCTURE OF METHYLBENZNE AND ETHYLBENZENE

Just the same but with an added CH3 or C2H5

Physical properties of aromatic hydrocarbons

1. Benzene, methylbenzene and ethylbenzene are liquids

2. Insoluble in water

3. Soluble in non polar solvents like cyclohexane

Uses of benzene

Opioids are full of benzoids