chemistry paper 2 Flashcards
what is a hydrocarbon
and compound formed from hydrogen and oxygen atoms only
what is the general formula of alkanes
CnH2n+2
are alkanes saturated or unsaturated
saturated
the shorter the hydrocarbon chain, the ….?
less viscous, more volatile and more flammable
what is the general formula of alkenes
CnH2n
are alkenes saturated or unsaturated
unsaturated
what can alkenes do that alkanes can not
form bonds from using the free carbon atoms. this makes them reactive
what is crude oil
a mixture of hydrocarbons former over many years
explain fractional distillation
oil is heated and enters the column as a vapour, longer hydrocarbons have high boiling pints and condense early on, shorter hydrocarbons have lower boiling points and condense at the top
what is cracking
when longer alkene molecules are turned into smaller, more useful ones
what kind of reaction is cracking
thermal decomposition
what catalyst is used in cracking
aluminium oxide
how do alkenes normally react
addition reactions
what is addition of hydrogen in an alkene
hydrogenation. it forms alkanes
what happens when water vapour reacts with alkenes
alcohols are formed
what happens when halogens react with alkenes
they form a saturated compound
how do alkenes burn
with a smoky flame. sometimes carbon and carbon monoxide are formed
functional group of carboxylic acids?
-COOH
what do carboxylic acids and alcohols form when reacted
esters
functional group of esters?
-COO
functional group of alcohols?
-OH
what are the properties of alcohols
they are flammable, the first 4 are soluble in water and they react with sodium, always producing hydrogen
how are polyesters made
condensation polymerisation
what is condensation polymerisation
monomers with different functional groups reacting together and forming bonds
what polymers make proteins
polypeptides via condensation polymerisation
what polymer is dna made from
two chains of nucleotides
how does dna get its double helix structure
the bases pair up with each other to form cross links
what temperature and pressure is equilibrium at for ammonium
450oC and 200 atmospheres
how do npk fertilisers assist with plant growth
they contain salts of nitrogen, phosphorus and potassium, which all affect growth
test for chlorine
bleaches damp litmus paper
test for oxygen
relights a glowing splint
test for carbon dioxide
turns limewater cloudy
test for hydrogen
puts out a splint with a squeaky pop
test for sulphates
add HCL and BaCL2 to a test tube, and see if it forms a white precipitate
how is ammonia collected
it is formed as a gas, but liquefies in the condenser and removed
