df3.0 alkanes

Developing Fuels DFDeveloping Fuels DF

DF

Developing FuelsHydrocarbons - Alkanes

Empirical Formulae

0.1g of hydrocarbon X on complete combustion gave 0.309g CO2 & 0.142g H2O. Calculate the empirical formulae of X? (2)

3 minutes to work it out !!

Empirical

1. C H

2. 12 1

3. C in CO2 H in H2O

(=12/44)x 0.309 (=2/18)x0.142

4. 0.0843/12 0.0158/1

0.00703 0.0158

5. 0.00703 0.0158

0.007030.00703

1 2.25 4 9

C4H9

1) Write out elements2) Write out RAM3) Calculate mass given

4) Moles = % or mass RAM

5) Ratio smallest for empirical (try to do smallest divide by both)

6) Whole numbers7) Formulae

Molecular Formulae

The relative molecular mass (Mr) of X was 114g by mass spectroscopy find the molecular formulae (1)

C8H18

Lesson Outcomes

Content Describe what an alkane is Explain the term saturated and branched Use the nomenclature system to name an alkane Investigate properties of alkanes

Process Investigation of winter

and summer blends Practice naming alkanes.

Benefit Introduction to

organic chemistry. Fuels we use

5 minute madness

Unilever chemistsWhat is an alkane? (6)

Proctor & Gamble chemistsUsing 5 carbon atoms and 12 hydrogen

make as many different models as you can – all of the atoms must be used up, winner is the on with the most.

Alkanes

Homologous series (1)Saturated (maximum no. of H) hydrocarbons (2)Only single bonds (1)Only C-C or C-H (2)General formulae of CnH2n+2 (1)They are mainly used as fuels, lubricants and

a starting material for many compounds/materials (2)

6 minute pictionary

Unilever ChemistsUse diagrams to explain how are

alkanes named?(6)

Proctor & Gamble ChemistsDraw your models out using structural

(i.e CH3CH2CH2CH2CH3)and display (stick) form

Nomenclature of alkanes

Root – longest C chain – use these prefix

Add “ane” for straight chained

pentane

If cyclic (CnH2n) add cyclo prefix to C chain root

(skeletal form)

cyclopentane

n Name

1 Meth-

2 Eth-

3 Prop-

4 But-

5 Pent-

6 Hex-

7 Hept-

8 Oct-

9 Non-

10 Dec-

Branched

Longest C chain is root – this is an alkane name

Count C where branch is

Branch is an “alkyl” group (CnH2n+1)

Name is root with “yl”

Address – no. , who & road

n Name

1 Methyl-

2 Ethyl

3 Propyl

4 Butyl

5 Pentyl

Write the name/draw these …..

3-propylheptane

Cyclobutane

2-ethylhexane

Ethylcyclohexane

2-methyloctane

Properties of alkanes

PolarityNon polar – why? Electronegativity similar between H & C

Solubility

Insoluble in H2O Mix with other non-polar liquids

Properties of alkanes

ReactivityNot with acids/bases/reducing or

oxidising agents Very well in O2 form CO2 & H2OReact with halogens

Properties of alkanes

Boiling pointShort chain (<5)are gases @ rm temp5-18 C liquid @ rm temp+18C solid @ rm tempBranches have lower MP/BP to same

mass straight chain

Demonstrate - DF3.1

Investigate summer/winter petrol blends

Which has the shorter chains?Why?Why do you think we need them to be

different?Why does it differ? (Draw lots of

molecules together to help you explain)

Review – SUPERMODEL

Model saturation using your tableModel a branched alkane with your table

Name it