Group 7 Flashcards
Trend in electronegativity in group 7
Decreases down the group
Trend in reactivity in group 7
Decreases down the group
Trend in BP in group 7
Increased down the group
Natural state of iodine
Diatomic
Grey solid
Sublimes to purple gas
Natural state of bromine
Red Brown liquid
Natural state of fluorine
Pale Yellow gas
Natural state of chlorine
Green gas
What happens in a reaction of KBr solution with Cl2?
Colourless to orange solution
Br2 formed, Cl displaces Br
What happens in a reaction of KI with Cl2?
Colourless to brown solution, I2 formed, displaced by Cl2
What happens in a reaction between KI and Bromine water?
Orange to brown solution. I2 formed, displaced by Br2
reaction for making bleach (disproportionation)
2NaOH +Cl2 =NaClO +NaCl +H2O
NaOH must be cold and dilute- The Chlorine in NaClO is oxidised, and in NaCl it is reduced
What are the two reactions of chlorine with water
Cl2 + H2O = 2H+ +2Cl- +1/2O2
IN SUNLIGHT:
Cl2 + H2O = 2H+ +2Cl- +1/2O2
BOTH REVERSIBLE REACTIONS
What are the problems of using chlorate (1) ions to kill bacteria, or treat water
Irritates the respiratory system
Liquid chlorine on the skin or in eyes can cause severe chemical burns
Chlorine can react with organic compounds to form chlorinated hydrocarbons which are carcinogenic
Trending in reducing power of halides
Increased down the group
Reducing agent- oxidised itself
Regenerate equation for initial reaction of Na Halides with sulfuric acid
NaX + H2SO4 = NaHSO4 + HX
What colour is Ca2+ in a flame test
Brick red
What colour is Sr2+ in a flame test
Red
Reaction of NaF with H2SO4
NaF + H2SO4 = NaHSO4 + HF
Reaction of NaCl with H2SO4
NaCl + H2SO4 = NaHSO4 + HCl
Misty fumes
Reaction of NaBr with H2SO4
NaBr + H2SO4 = NaHSO4 + HBr
2HBr + H2SO4 =Br2 +SO2 +2H2O
Misty fumes
Choking fine of SO2 and Orange Fumes Br2
Reaction of NaI with H2SO4
NaI + H2SO4 = NaHSO4 + HI
2HI + H2SO4 = I2 + SO2 + 2H2O
6HI + H2SO4 = H2S + 3I2 + 2H2O
Misty fumes
Solids grey iodine
