Organic Chemistry 10 Chemistry

Quiz

Alkanes General Formula Description Combustion Reactivity Chemical test Uses C n H 2n+2 Saturated Burns in Oxygen to form CO 2 + H 2 0 (CO with low O 2 ) 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 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

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 carbons atoms

Combustion combustion

Viscosity

Homework Go to: oilstrike.org/preloader.swfhttp:// 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

Alkanes

The end of year test Can contain ANYTHING we have covered over the course of this year (see specific learning objectives) May contain anything from the Organic Chemistry too

Origami time Youtube

Homologous series A family of hydrocarbons is a homologous series This means they have the same functional groups You can have alcohols (ROH), alkanes (R- H), Haloalkanes (RX) and MANY OTHERS Roger Frost

Isomerism Hydrocarbons are based upon the number of carbon atoms The carbon atoms can be rearranged in different ways: these are called isomers

Alkenes

Formed from cracking One or more double carbon bond Hence unsaturated Reactivity due to double bond Tested with bromine water

Alkenes

General Formula Description Combustion Reactivity Chemical test Uses C n H 2n unsaturated Burns in Oxygen to form CO 2 + H 2 0 (CO with low O 2 ) High (double bond), undergo addition reactions Turns bromine water from brown to colourless Making polymers

Isomers of Alkenes

Questions Q1 (a) Draw displayed formulae for hexene (b) Describe a test to distinguish between hexane and hexene Q2 Draw two isomers of pentene Homework: revise

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