Group 7 Properties Flashcards
Iodide with silver nitrate
Yellow precipitate
Bromide with silver nitrate
Cream precipitate
Chloride with silver nitrate
White precipitate
Fluoride with silver nitrate
No visible change
Equation for reaction between NaCl and H2SO4
NaCl + H2SO4 = NaHSO4 + HCl
Observation from reaction between NaCl and H2SO4
White Steamy fumes
Equation for reaction between NaBr and H2SO4
NaBr + H2SO4 = NaHSO4 + HBr
2HBr + H2SO4 = Br2 + SO2 + 2H2O
REDOX H2SO4 acts as an acid to produce HBr then an oxidising agent
Observation of reaction between NaBr and H2SO4
White Steamy fumes
Red fumes of bromine
Equation for reaction between NaI and H2SO4
NaI + H2SO4 = NaHSO4 + HI
H2SO4 acts as an acid in th3e first step to produce HI then as an oxidising agent in the 3 redox steps
2 HI + H2SO4 = I2 + SO2 + 2 H2O
6 HI + H2SO4 = 3 I2 + S + 4 H2O
8 HI + H2SO4 = 4 I2 + H2S + 4 H20
Observation of reaction between NaI and H2SO4
White steamy fumes Purple fumes OR Black Solid Yellow sulphur solid Pungent smell
Trend in MP and BP in group 7
MP and BP increase down the group
More VDW forces because increasing number of electrons
Trend in electronegativity in group 7
Electronegetivity decreases down the group
Increasing atomic radius
distance between nucleus and electrons
less able to attract them in a bond
Trend in Oxidising strength in group 7
oxidising strength decreases down the group
Electron acceptor
What does the colour of a displacment solution tell you
the colour shows the free or displaced halogen present in solution
Trends in displacement in group 7
Chlorine displaces bromide and iodide ions
Bromine will displace iodide
Eg) Cl2 + 2Br- = 2Cl- + Br2
Silver Halide reactions with ammonia
Silver chloride dissolves in DILUTE ammonia- colourless solution
Silver bromide dissolves in CONCENTRATED ammonia- colourless solution
Silver iodide doesn’t react with ammonia- too insoluble
Trends in halides as reducing agents
Increasing power as a reducing agent down the group
(electron donator)
As ion increases in size FoA decreases because of additional shells making it easy to lose outer electron
Sodium Fluoride and chloride reactions with H2SO4
And observation
Not strong enough to reduce S (No REDOX, acid base reaction)
Observe white steamy fumes
NaF + H2SO4 = NaHSO4 + HCl
Reduction products of Bromide with H2SO4
Sulfur dioxide
Reduction products of Iodide with H2SO4
Sulfur dioxide
Sulfur
Hydrogen sulfide
Define disproportionation
a reaction where an element simultaneously oxidises and reduces
Chlorine with water (Disproportionation)
Cl2 + H2O = HClO + HCl
if universal indicator added, first turn red due to acidic products, then colourless as HClO bleaches it
Chlorate
ClO3 1-
Reaction of chlorine with water in bright sunlight
2Cl2 + 2H2O = 4H+ + 4Cl- + O2
