Df3.0 Alkanes
-
Upload
loopychemlass -
Category
Technology
-
view
731 -
download
1
description
Transcript of 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