14:Halogens Flashcards
What is the appearance of chlorine at room temperature
Green/yellow gas
What is the appearance of bromine at room temperature
Red-brown liquid giving off a brown vapour
What is the appearance of iodine at room temperature
Grey/black solid (which on gentle heating, vapourises to form a purple gas)
How does reactivity change going down group 7
Reactivity decreases
What colour is aqueous solution and cyclohexane layer of chlorine
Aqueous solution: Pale yellow
Cyclohexane: Pale yellow
What colour is aqueous solution and cyclohexane layer of Bromine
Aqueous solution: Orange
Cyclohexane: Orange
What colour is aqueous solution and cyclohexane layer of Iodine
Aqueous solution: Brown
Cyclohexane: Purple
What colour precipitate does chlorine form when reacting with silver ions
White precipitate
What colour precipitate does bromine form when reacting with silver ions
Cream precipitate
What colour precipitate does Iodine form when reacting with silver ions
Yellow precipitate
Does silver chloride dissolve in dilute or concentrated aqueous ammonia
Dilute and conc
Does silver bromide dissolve in dilute or concentrated aqueous ammonia
Concentrated only
Does silver iodide dissolve in dilute or concentrated aqueous ammonia
Niether
What is the reaction between aqueous chlorine with water
Cl₂(aq) + H₂O(l) → HCl(aq) + HOCl(aq)
Disproportionation reaction
What is a disproportionation reaction
The same element is simultaneously oxidised and reduced
Why do some people have concerns about the use of chlorine in water treatment
- Chlorine itself is highly toxic
- Chlorine can also react with traces of organic compounds in water, producing organochlorine compounds, some of which are known as carcinogens
Reaction of aqueous chlorine and cold, dilute aqueous sodium hydroxide
Cl₂(aq) + 2NaOH(aq) → NaCl(aq) + NaClO(aq) +H₂O(l)
Why is the reaction of chlorine and cold, dilute aqueous sodium hydroxide commercially used
Produces NaClO sodium chlorate(I) which is bleach
