ES Flashcards
Colours of halogens dissolved in cyclohexane
Chlorine: pale green
Bromine: orange/brown
Iodine: violet
What end of the group is the stronger oxidising agent?
Top
Which end of the group is most soluble in ammonia?
Top
Cations, anions, cathode, anode
Cations (+) go to cathode (-)
Anions (-) go to anode (+)
What is the product at the cathode?
Metal or hydrogen
Hydrogen: group 1/2 or acids
-2H20 + 2e- –> H2 + 2OH-
Hydrogen for acids
- 2H+ + 2e- –> H2
Metal: everything else
Reduction = + e-
What is the product at the anode?
Halogen if present
Oxygen
- if sulfate or nitrate: 2H2O –> O2 + 4H+ + 4e-
- if hydroxides: 4OH- –> O2 +2H2O + 4e-
Iodine thiosulfate titration
Oxidation of I-
Iodide added to excess ClO-
I2 produced can be added to S2O3 2-
End point = starch = blue/black no longer visible
Sodium fluoride/chloride + sulfuric acid
NaHSO4 + HCl/HF
Sodium bromide + sulfuric acid
NaHSO4 + HBr
Stronger oxidising agent = reduces further
SO2 + H2O + Br2
Sodium iodide + sulfuric acid
H2S + 4I2 + 4H2O
Thermal stability down group 7
Decreases
Bond strength decreases
Hydrogen halides - heating
Only HBR/HI break down into H2 and halogen
Hydrogen halides - acidity
All acidic in solution
Fully dissociate
H3O+
Hydrogen halides - sulfuric acid
Only HBr/HI react
SO2
H2S
What is the equation for atom economy?
mr of useful product/mr of all reactants
