Organic Chemistry

10 Chemistry

Quiz

Alkanes

• General Formula• Description• Combustion

• Reactivity• Chemical test• Uses

• CnH2n+2

• Saturated• Burns in Oxygen to

form CO2 + H20 (CO with low O2)

• Low• None• Fuels

The chlorination of methane

• Halogenation is the replacement of one or more hydrogens in an organic compound by halogen atoms

• When methane is reacted with chlorine the products of the reaction depend on whether there is an excess of methane or chlorine

• If there is an excess of methane it form chloromethane and hydrogen chloride

To do

• Write down a word equation for the chlorination of methane

• Can you write a chemical equation?

• How about a full balanced chemical equation?

Movie

Halogenation

chloridehydrogenanechloromethchlorinemethane

HClClCHClCH 324

)()()()( 324 gHClgClCHgClgCH

With an excess of chlorine a mixture of products is formed. Chlorine can obviously replace up to 4 of the hydrogen atoms.

Why halogenation?

• These products are generally used as intermediate compound for further synthesis

Natural Gas and Oil

Separating the fractions

Fractional distillation

• Preheated crude oil is pumped into the column (340 C)

• The vapour in the crude oil rises due to differences in density with different fractions condensing in different regions

• The liquid part of the crude oil sinks in the column

• The low density fractions are thin and light coloured, the high density fractions are ‘viscous’ and dark

http://upload.wikimedia.org/wikipedia/commons/6/62/University_of_Queensland_Pitch_drop_experiment-6-2.jpg

How does it work?

• Components separate due to different boiling points

• Crude oil is a mixture of hydrocarbons

• Molecules are chemically bonded with strong covalent bonds but contain different numbers of carbon atoms

Go on…

• The weak attractive forces between the molecules have to be broken if the hydrocarbon is to boil

• The longer the hydrocarbon molecule is, the stronger the intermolecular forces are

• The shorter chains are more volatile – they form a vapour

Boiling

Volatility

• We can smell petrol (gasoline) much easier than we can smell engine oil

• This is because petrol has 5-10 carbon atoms and engine oil has 14-20 carbons atoms

Combustion

combustion

Viscosity

Viscosity

http://www.rsc-oilstrike.org/preloader.swf

Homework

• Go to: http://www.rsc-oilstrike.org/preloader.swf

• Play the game

• Take a screen shot (print screen) or use the snipping tool to take an A4 image

• Print this out and stick it in

• Winner (most money) gets a ‘get out of homework free’ card

Incomplete Combustion