Chapter 6 Flashcards
(40 cards)
What are the names for the functional group of
1.carboxylic acid
2.alcohol
3.ketone
4.aldehyde
1.ethanoic acid
2.ethanol
3. Ethanone
4. Ethanal
What are the three types of isomerism
Chain isomers: Sam’s molecular formula but one is linear and other is branched E.g butane and methyl propane
Position isomers:same molecular formula but function group in different place E.g butan-1-ol and butan-2-ol
Functional group isomers: isomers that had truer structures changed so different functional group E.g propanoic acid and methyl ethanoate
What and where are sigma bonds
C-H and C-C bonds are sigma bonds
In sigma bonds, the electron orbitals overlap directly between the 2 atomic nuclei
These bonds also allow free rotation of the atoms at either end
whats the bond shape of the carbon in every alkane
tetrahedral-109.5
how does boiling point change with branching
longer chained molecules have higher boiling point than branched alkanes
this is is because longer chains have higher chance for induced dipole-dipole interactions when they’re next to each other
what is the reactivity of alkanes and why
not very reactive as high bond enthalpy
sigma bonds means no bond polarity
what is crude oil and how is it formed
a none renewable resource formed by fossilised remains of plankton
made of lots of compounds but mainly hydrocarbons
whats the steps of fractional distillation
- evaporation- crude oil is heated until evaporated, where the vapour is put into a fractionating column at the bottom and rises up
- condensation- the temperature is highest at the bottom of the column. Long chain hydrocarbons condense at the bottom and are collected as liquids. shorter chains will pass upwards to condense at the cooler levels
- collection- the fractions are collected and processed to make fuels, feedstock, solvents, lubricants, detergents etc
what is cracking and what are the 2 types
process of turning alkanes into alkenes +shorter alkanes
thermal cracking: uses high temp and high pressure
breaks alkanes into high % of alkenes
done at 1000 degrees celsius and 70atm pressure
catalytic cracking: using a catalyst allows for lower temps, pressure cost and is faster
tend to get molecules with benzene rings rings and short hydrocarbons
dont at 450 celsius and zeolite catalyst (zeolite is compound of Al, Si and O) and just above atmospheric pressure
what is the difference between complete an incomplete combustion
complete: blue flame and only produces CO2 and H2O
incomplete: orange smoky flame- orange because of small particles of pure carbon glowing red hot
produces CO2 H2O, pure carbon, hydrocarbons and CO
incomplete combustion is more likely with longer alkanes and they need more O2 to completely combust
what are the bad effects of combustion
can make impurities like nitrous oxide, unburned hydrocarbons and CO
nitrous oxides react to make ozone at ground level, which causes irritation and causes lung damage
flue gasses are what come out of chimneys ad usually have sulphur dioxide -sulphur dioxide dissolved in water to make sulfuric acid which becomes acid rain
how to remove chemicals produced by combustion
remove sulphur dioxide by reacting with calcium oxide or calcium carbonate - this is because sulphur dioxide is acidic and calcium oxide is basic
equation is: CaO + SO2 = CaSO3
remove unburned hydrocarbons and nitrogen oxides with catalytic converters
explain chlorination
chlorination uses free radicals
products: excess methane, chloromethane is made
with excess chlorine, multiple reactions happen to get tetrachloromethane
3 steps (applies to all free radical reactions)
-initiation
-propagation
-termination
Conditions: UV light
what are the steps of free radical substitution with CH4 and Cl2
- initiation- CL2 = 2Cl*
propagation
- CH4 +CL* = CH3* + HCl
- CH3* +CL2 = CH3Cl + Cl*
termination
-2CH3 =C2H6
-2CL* =Cl2
-CH3* +Cl* = CH3Cl
what are alkenes
unsaturated hydrocarbons with double bond- 2 less hydrogens than alkanes with = carbons
give properties of alkenes
CnH2n is gneral formula
they’re hella reactive because double bond has hella electron density
double bond is made of 1 sigma and 1 pi bond
pi bond uses P orbitals above + below plane of c=c bond-this makes the C=C unable to rotate
free throw
what are the reactions of alkenes
react with many reagents in addition reactions
they’re nucleophiles because high electron density in double bond
dose electrophilic addition
reacts similar with sulfuric acid and bromine
whats the end product of the electrophilic addition with:
- sulfuric acid and water
-Br2
-HBr
-alcohol
-an alkane with 2 bromines instead of 2 hydrogens -C2H4Br2
-C2H5Br
whats the uses of electrophilic addition
with bromine- used as a test for alkenes
bromine water is a light orange colour and will become colourless in presence of alkene- this works because bromine can add to alkenes through electrophilic addition
with sulfuric acid- produces alcohols- the sulphate ion is removed by nucleophilic substitution
what happens when an asymmetrical alkene undergoes electrophilic addition
with an asymmetrical alkene there can be multiple products
a reaction will favour one of the products over the other one-selectivity- shown in reaction of propene and HBr
how does intermediate stability affect selectivity in electrophilic substitution
driven by carbocation intermediate stability
tertiary hydrocarbons> secondary carbocations > primary carbocations
the more alkyl groups are next to the positive charge there more stable the intermediate is
Ts is because alkyl groups push electrons and so help stabilise adjacent positive charge
how to tell which product is formed in electrophilic substitution
2 bromopropane is most likely to be formed because the intermediate is a secondary carbocation , opposed to a primary carbocation
both reactions will happen and both products will be formed, but one major product and 1 minor product
how to tell if a reaction uses electrophilic addition
the reactants are an alkene + halogen/ H2SO4
what are the properties of polymers
polymers have Van der Waals forces- they’ve hella van der Waals
branch cahin polymers pack less densley and are more flexible
