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3a + 3b + 3c) ORGANIC CHEMiSTRY (Alkenes (butene: C4H8 decene: C10H20,…
3a + 3b + 3c) ORGANIC CHEMiSTRY
Hydrocarbon
= a compound containing hydrogen and carbon only.
Homologous series
a series of compounds each differing by CH2.
they have
similar chemical properties
and show a
trend in physical properties
All members have the
same general formula
Formulae
Molecular formula
the actual number of atoms within a molecule
General formula
A formula which can apply to all members of a homologous series
Displayed formula
shows
all
bonds present
Structural formula
Shows structure without showing all bonds.
Saturation
Saturated
Any organic compound containing only single covalent bonds
Unsaturated
any organic compound containing one (or more) double covalent bonds
Functional group
atom 1 group of atoms, which gives a compound its characteristic behaviour e.g. c=c double bond in alkanes
isomerism
when two or more chemicals have the same molecular formula, but a different arrangement of atoms
what is organic chemistry?
the study of the compounds of carbon
Alkanes
alkanes are saturated
they contain single bonds only
they are a homologous series of hydrocarbon molecules
Methane = meth 1 C, CH4
Ethane = eth 2 C, C2H6
Propane = prop 3 C, C3H8
Butane = But 4 C, C4H10
Pentane = pent 5 C, C5H12, Isomers of Pentane = dimethylpropane and methylbutane
Isomers are molecules with the same molecular formula but different arrangements of atoms
complete combustion = the burning of a chemical in air with excess oxygen present
the products of complete combustion with hydrocarbons is always CO2 and H2O
equations for complete combustion
methane
CH4 + 2O2 → CO2 + 2H2O
butane
2C4H10+13O2 → 8CO2 + 10H20
it binds to the haemoglobin in preference to oxygen
what chemicals may be produced from incomplete combustion of an alkane?
water still formed but carbon monoxide (CO) &/or soot (C) may form instead of CO2. CO is toxic
2 equations for incomplete combustion of octane
C8H18 + 8O2 → 9H2O + 1C + 7CO
C8H18 + 9O2 → 9H2O + 7CO + CO2
Alkenes
butene: C4H8 decene: C10H20
ethene = 2 C, C2H4, CH2=CH2C, empirical formula=CH2
from butene upwards the double bond can go anywhere in the carbon chain
propene= 3 C, C3H6, CH2=CHCH3, empirical formula=CH2
But-1-ene=C4H8, CH2=CHCH2CH3, empirical formula=CH2←C3H6
but-2-ene=4 C, C4H8, CH3CH=CHCH3, empirical formula=CH2←C4H8
an alkene is an unsaturated hydrocarbon which contains ONE c=c bond
The -ene ending indicates it is an alkENE
the 1 or 2 is used to indicate if the double bond is attached to the end carbon (1) or the next carbon along (2) (butane/pentane only)
pentane= c-c=c-c-c
the prefix to indicate the number of carbon atoms in the chain is the same as for alkanes - CnH2n+2
The third alkene isomer is for C4H8. This is methylpropene