topic 4 Flashcards
what is the reactions of group 2 metals with oxygen
metal + oxygen -> metal oxide
what is the reactions of group 2 metals with chlorine
metal + chlorine -> metal chloride
what is the reaction of group 2 metals with water
metal + (cold) water -> metal hydroxide + hydrogen
what are the group 1 flame colours
lithium- red
sodium- yellow
potassium- lilac
rubidium- red
caesium- blue
what are the group 2 flame colours
magnesium- no flame colour
calcium- orange-red
strontium- red
barium- pale green
copper- blue-green
why does magnesium have no flame colour
energy released isnt in visible light spectrum
what colour is chlorine at room temperature
pale green gas
what colour is bromine at room temp
brown liquid
what colour is iodine at room temp
grey-black solid
what colour is chlorine in aqueous solution
pale green
what colour is bromine is aqueous solution
orange/yellow
what colour is iodine in aqueous solution
brown
what colour is chlorine when dissolved in a hydrocarbon solvent
pale green
what colour is bromine when dissolved in hydrocarbon solvent
red
what colour is iodine in hydrocarbonsolvent
purple
what is the experimental procedure for thermal decomposition
-measure some of the carbonate into a test tube
- fit a delivery tube to the test tube and clamp it so that the delivery tube end in a second test tube containing limewater
- heat the test tube containing the carbonate and then heat it more strongly
how can you test for chlorine
chlorine turns damp blue litmus red and then bleaches it
chlorine also displaces bromine and iodine from bromide or iodide solutions
how can you test for bromine
bromine is orang/red when dissolved in an organic solvent
bromine displaces iodine from an iodide solution
how can you test for iodine
iodine turns starch black
is also decolourised by thiosulphate solution
its brown in water but purple in organic solvents
what kind of solvents do halogens dissolve in
non polar solvents such as hexane
why does the colour change occur in halogen displacement reactions
when the halogn is displaced, the solution turns into the colour of the halogen that is displaced in aqueous solution
e.g if iodine is displaced, aqueous solution would turn brown (which is its colour when dissolved in aqueous solution)
why does reducing power increase down group 7?
this is because the halide ion becomes larger
outer electrons are further from the nucleus
less attraction between the nucleus and the outer e-
easier to lose e- do it can be used to reduce other species (and donate its electron)
when concentrated sulfuric acid is added to (e.g potassium) chloride what can be produce
misty white fumes
hydrogen halide is formed
KHSO4
when concentrated sulfuric acid is added to (potassium) bromide what can be produced
brown misty fumes
bromine gas is formed
sulphur dioxide is formed
when concentrated sulfuric acid is added to (potassium) iodide what can be produced
iodine gas
water
sulphur dioxide
suphur
hydrogen sulphide
what are the colours of the precipitates formed when silver nitrate is added to halides
silver halide forms
silver chloride- white
silver bromide- cream
silver iodide- yellow
what is the effect of sunlight on the halides
chloride- white precipitate turns purple- grey
bromide- cream precipitate turns green- yellow
iodide- no effect
what happens when ammonia solution is added to halides
chloride- precipitate dissolves in dilute and conc. ammonia solution
bromide- precipitate dissolves in conc. ammonia solution
iodide- doesnt dissolve
what is the disproportionation reaction of chlorine with water
Cl2(g) + H2O(l) -> HClO(aq) + HCL(aq)
what is the reaction of chlorine with cold dilute sodium hydroxide
disproportionates to chlorate (I) and chloride
2NaOH + CL2 -> NaCl + NaClO + H2O
what is the reaction of chlorine with hot concentrated sodium hydroxide solution
3Cl + 6NaOH -> 5NaCl + NaClO3 + 3H2O
how do you test for carbonate ions
add dilute hydrochloric acid is added to the test compound
bubbles of gas produced which is carbon dioxide
limewater is used to confirm that the gas is CO2
how to test for sulphate ions
detected using barium chloride
- add a few drops of dilute hydrochloric acid
- then add a few drops of barium chloride solution
- a white precipitate of barium sulphate forms if sulphate ions are present
how can you test for ammonium ions (NH4+)
- add dilute sodium hydroxide and gently warm
is ammonium ions present - ammonia gas will form - ammonia gas turns damp red litmus paper blue
What is the formula for group 1 carbonates
X2CO3
What is the formula for group 2 nitrates
X(NO3)2
What is the formula for group 1 nitrates
XNO3
What is the formula for group 2 carbonates
XCO3
why is iodine unable to displace bromine or chlorine
its a weaker oxidising agent than them both
how can you compare the rate of decomposition of carbonates
use of delivery tube to bubble gas into limewater
compare time taken for lime water to go cloudy
what is the trend in reactivity of haloalkanes
increases down the group
this is because the C-X bond enthalpy decreases
