group 7 - the halogens

?
what are the isotopes and abundances of fluorine?
F19 = 100%
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what are the isotopes and abundances of chlorine?
Cl35 = 75%
Cl37 = 25%
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what are the isotopes and abundances of bromine?
Br79 = 50%
Br81 = 50%
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what are the isotopes and abundances of iodine?
I127 = 100%
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what is the appearance of fluorine at room temp?
pale yellow gas
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what is the appearance of chlorine at room temp?
green gas
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what is the appearance of bromine at room temp?
dark red volatile liquid
brown vapour
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what is the appearance of iodine at room temp?
shiny black solid that sublimes to give a purple vapour
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define volatile
evaporates easily
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define sublimes
goes from a solid straight to a gas
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state and explain the trend in boiling points of the halogens down the group
increases
as the size of the molecule increases there are more van der Waals so more energy is needed to break these intermolecular forces
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define atomic radius
distance from nucleus to the outer electron
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State and explain the trend in atomic radius down Group 7
increases as there is an extra shell of electrons so more shielding and weaker electrostatic force of attraction between nucleus and outermost electron
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Define electronegativity
Ability of an atom to attract the shared pair of electrons in a covalent bond
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state and explain the trend in electronegativity down group 7
decreases as the size of atom increases so more shielding and the attraction
between the nucleus and the bonding pair of electrons decreases.
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what is an oxidising agent?
an electron acceptor
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which of the halogens will be the strongest oxidising agent and why?
fluorine as has the highest electronegativity so more attraction from the nucleus
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will the reaction between iodine and chloride happen.
what will be observed
no
stays a brown solution
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will the reaction between chlorine and iodide happen
what will be observed
yes
changes from pale green to brown solution
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will the reaction between bromine and chloride happen
what will be observed
no
stays an orange solution
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will the reaction between bromine and iodide happen
what will be observed
yes
changes from orange to brown solution
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will the reaction between chlorine and bromide happen
what will be observed
yes
changes from pale green to orange solution
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will the reaction between iodine and bromide happen
what will be observed
no
stays orange solution
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what is required for the reaction to occur between a halide and a halogen?
the halogen must be higher up in the group than the halide
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determine the trend in oxidising power of the halogens
decreases down group 7
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what is the equation for the extraction of iodine from kelp
2I–+ MnO2 + 4H+ ------->Mn2+
+ 2H2O + I2
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what is the role of MnO2 in the extraction of iodine from kelp
oxidising agent
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what is the observation on adding AgNO3 to fluoride
no precipitate
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what is the observation on adding AgNO3 to chloride
white precipitate
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what is the observation on adding AgNO3 to bromide
cream precipitate
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what is the observation on adding AgNO3 to iodide
yellow precipitate
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what is the observation on adding dilute NH3 to
ppt remains
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what is the observation on adding dilute NH3 to chloride
ppt dissolves
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what is the observation on adding dilute NH3 to
ppt remains
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what is the Observation on
adding conc. NH3 to bromide
ppt dissolves
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what is the Observation on
adding conc. NH3 to iodide
ppt remains
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explain why the solution need to be acidified when testing for halide ions?
To remove carbonate and hydroxide impurities which would give a false positive result
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Why can’t you use hydrochloric acid instead of nitric acid when testing for halide ions?
HCl contains chloride ions and would react with the Ag+ ions to form AgCl and give a false positive result
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On addition of silver nitrate to an acidified solution a white precipitate developed which
disappeared on addition of dilute ammonia – identify one ion in the original solution
Cl-
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Write an equation showing the reaction of chlorine (Cl2) with a solution of potassium
iodide (KI)
Cl2 + 2KI → 2KCl + I2
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Write the two half equations occurring when chlorine is added to a solution of
potassium iodide
Cl2 + 2e− → 2Cl−
2I− → I2 + 2e−
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write the equations for the reactions between H2SO4 and fluorine
NaF + H2SO4 ----> NaHSO4 + HF
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write the equations for the reactions between H2SO4 and chlorine
NaCl + H2SO4 -----> NaHSO4 + HCl
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write the equations for the reactions between H2SO4 and bromine
NaBr + H2SO4 -----> NaHSO4 + HBr
2HBr+H2SO4 → SO2 + Br2 + 2H2O
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write the equations for the reactions between H2SO4 and iodide
NaI+H2SO4 → NaHSO4 + HI
2HI+H2SO4 → SO2 + I2 + 2H2O
6HI+H2SO4 →S+ 3I2 + 4H2O
8HI+H2SO4 →H2S+ 4I2 + 4HO
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what can you observe with HCl
white misty fumes
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what can you observe with SO2
colourless choking gas
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what can you observe with Br2
orange gas
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what can you observe with I2
purple vapour
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what can you observe with S
yellow solid
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what can you observe with H2S
bad egg smell
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what is the equation for the reaction of chlorine with water in sunlight?
2Cl2 (g) + 2H2O (g) ----> 4HCl (g) + O2 (g)
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what is the equation for the reaction of chlorine with cold dilute aqueous NaOH
Cl2(g) + 2NaOH (aq) -----> NaCl (aq) + NaClO (aq) + H2O (l)
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Other cards in this set

Card 2

Front

what are the isotopes and abundances of chlorine?

Back

Cl35 = 75%
Cl37 = 25%

Card 3

Front

what are the isotopes and abundances of bromine?

Back

Preview of the front of card 3

Card 4

Front

what are the isotopes and abundances of iodine?

Back

Preview of the front of card 4

Card 5

Front

what is the appearance of fluorine at room temp?

Back

Preview of the front of card 5
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