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The properties of group 7 elements
What is the trend in bpt down the group, why?
-increases down the group
-atom gets bigger so stronger VDW forces
Why is HNO3 added instead of HCl in halide tests
to remove carbonate ions
Adding HCl would add Cl- ions which would give a false positive result
What is the result and equation for the Cl- test
Ag+ + Cl- —> AgCl (s)
What is the trend in oxidising ability down the group?
Why?
it decreases down the group
Cl has the fewest occupied electron shells and the greatest attraction between the outer electrons and the nucleus
This means it gains electrons the easiest
What are the products formed when I- reduces H2SO4 and what are the equations for each?
Why is ozone not used to purify water in the uk
It is more expensive and evaporates from the water quicker than chlorine
What is the equation for the reaction of Cl2 with water?
What type of reaction is the reaction of chlorine with water
disproportionation
The chlorine is both oxidised and reduced
What are the two forms of the chlorate ion
What is the equation for making bleach
What is the definition of desalination
The process that converts salt water into clean potable water through either reverse osmosis or distillation
What are the advantages and disadvantages of desalination
Advantages:
Makes safe, clean drinking water
Disadvanges
Uses lots of energy, may disturb marine life, expensive
Note 
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