Unit 5 revision Flashcards
key points and or definitons in unit 5 of aqa a level chemistry
what is nomenclature?
the process of naming organic compounds
what is structural ismoerism?
where two molecules have the same molecular formula but different structures
what is molecular formula
the actual number of atoms of each element in a compound
what is structural formula?
the formula that shows the unique arrangement of atoms in a molecule
what is skeletal forumla?
a formula where staight lines represent carbon bonds,
what is the suffix for aldehydes?
-al
what is the suffix for the ketones?
-one
what is the suffix for the carboxylic acids?
-oic acid
what is the suffix for the alcohols?
-ol
what is the functional group of the aldehydes?
a carbon double bonded to oxygen and a single bond to a hydrogen
what is the functional group of the alcohols?
R-OH
what is the functional group of the ketones
C=O
what is the functional group of the carboxylic acids
carbon atom double bonded to a oxygen atom and a seperate single bond to an OH group
what is the functional group of the alkenes
C=C
name two features of a homolgus series
they each have the same functional group
they increase by CH2
what is a chain isomer?
where the hydrocarbon chain is arranged differently
what is a functional isomer?
molecules with the same molecular formula but different functional groups
what is a positional isomer?
the functional group is attached to the main chain at different points
what E-Z isomerism?
where substituents are at either side of a carbon-carbon double bond cis-same side or trans-opposite side
why are alkanes non polar?
due to the electronegativity of carbon and hydrogen being too similar
why do the boiling points of alkanes increase?
as the chain lengths increase so they have more van der waals forces as there are more electrons between atoms.
why do branched alkanes have a lower boiling point than unbranched alkanes?
they cannot pack together so closely as unbranched chains and so they have less effective van der waals forces.
why are alkanes insoluble in water?
as water molecules are held together by hydrogen bonds which are alot stronger than van der waals forces.
describe the process of fractional distillation of crude oil
(5-points)
- crude oil is heated to around 350 degrees celcius
- it is then passed into a distillary column
- the fractions evaporate and rise up the column
- when they reach their boiling points they condense and are collected.
- all fractions except for bitumen evaporate
what is cracking?
the process of breaking longer chain hydrocarbons into shorter chain more useful hydrocarbons
name one advantage of cracking being preformed in industry
it cuts down waste and allows for the creation of more useful products that can be sold on to create a profit
name the conditions of thermal cracking
.700-1200kelvin
.pressure of around 7000kpa
describe the process of thermal cracking
the hydrocarbon is heated breaking the covalent bond between two carbon atoms each of these recieve an electron, these form two shorter chain alkanes and an alkene.
what is a free radical?
molecules with free electrons these are highly reactive
name the conditions of catalytic cracking
cataylist is present
temperature of around 720K
pressure greater than 1 atmospheric pressure
what is the catalyst in catalytic cracking?
zeolites which consist of silicon dioxide and aluminium oxide
describe the shape of a zeolite catalyst and why this shape helps
honeycomb shape to give an enormous surface area
how are the products of cracking seperated?
by fractional distillation
name the products of complete alkane combustion?
carbon dioxide and water
name the products of incomplete alkane combustion
carbon( if there is too little oxygen) carbon monoxide and water
why is carbon monoxide dangerous?
it is a toxic gas that binds to the haemoglobin in the red blood cells causing death by asphyxiation
how is sulfur dioxide produced?
it comes from the sulfur impurities present in crude oil
and coal combustion
what does sulfur dioxide contribute towards?
acid rain
how is sulfur dioxide removed from the atmosphere?
it is reacted with calcium carbonate(CaCo3) this forms gypsum which is a useful building material
what do particulates cause and contribute towards?
- cause cancer
- contribute towards global dimming
how are nitrogen oxides formed?
when there is enough energy for nitrogen and oxygen in the air to combine.
what do nitrogen oxides contribute towards?
acid rain and photochemical smog
how are nitrogen oxides and carbon monoxide removed from the atmosphere?
by catalytic converters in cars
whats is the catalyst and shape of a catalytic converter?
honeycomb made of cermaic coated with platinum
what do carbon monoxide and nitrogen oxide form in a cataylitic converter?
carbon dioxide and nitrogen
why are haloalkanes polar?
as they have a large enough difference in electronegativity between the carbon and halogen
why won’t haloalkanes mix with water but mix with hydrocarbons
as they are not polar enough to mix with water but polar enough to mix with hydrocarbons
what happens to the boiling points of haloalkanes
they increase as the chain length of carbons get longer
they decrease with branching of the carbon chain
what is the most important factor when determining the reactivity of haloalkanes?
bond enthalpy
what is a nucleophile?
a negtatively charged ion or has an atom with a delta - charge that has a lone pair of electrons
what is nucleophilic substitution?
a reaction in which a molecule with a partially positively charged carbon ion is attacked by a reagent with a negatvie charge or partially negatively charged area, one of the groups or atoms in on the original molecule is replaced by the nucleophile
what is an elimination reaction?
a reaction in which an atom or group of atoms is removed from a reactant
