FC14 Halogens Flashcards
Write the equation for the reaction between Chlorine and dilute, cold, aqueous sodium hydroxide
Cl2 + 2NaOH -> NaCl + NaClO + H2O
How do we chlorinate our water
H2O + Cl2 -> HCl + HClO
What type of reaction is making bleach and chlorination of water
Disproportionation
How do you make bleach and write out the equation
React chlorine with cold dilute aqueous sodium hydroxide
Cl2 + 2NaOH -> NaCl + NaClO + H2O
State and colour at RTP of Fluorine
Pale yellow gas
State and colour at RTP of Chlorine
Colour in non polar solvent and colour in aqueous solution
Pale green gas at RTP
Pale green and very pale green
State and colour at RTP of bromine
Colour in non polar solvent and aqueous solution
Volatile red brown liquid at RTP
Orange and orange/yellow if dilute
State and colour at RTP of iodine
Colour in non polar solvent and aqueous solution
Grey black solid at RTP
Violet and brown/yellow if dilute
What is trend in mpt/bpt in halogens down the group and why
Increasing due to an increase in number of electrons per molecule and increase in surface area of each molecule going down the group therefore the strength of London forces between molecules increase and more energy is needed to break the intermolecular forces
What is the trend in reactivity in halogens down the group and why
the halogens become less oxidising as we go down group 7. Going down group 7, the nuclear charge increases and the number of electron shells increases, the greater shielding outweighs the greater nuclear charge, and so the attraction between the nucleus and an electron from another species decreases, so the ability to remove an electron from another species (and oxidise it) decreases
What are the three halogen halide displacement reactions that occur out of chlorine, bromine, iodine, in their halides
chlorine displaces both bromine and iodine from their halides
bromine displaces iodine from its halide
What is the first step of testing for halides
add dilute nitric acid to remove any carbonate ions that will give a false positive result, as silver carbonate is a white precipitate
What is the second step of testing for halides
Add aqueous silver nitrate to the suspected halide, silver halide precipitate will form if halide present
silver chloride = white ppt
silver bromide = cream ppt
silver iodide = yellow ppt
What is the third step of testing for halides
Add dilute ammonia solution, then concentrated ammonia solution
AgCl will dissolve in both
AgBr will dissolve in conc only
AgI is insoluble in both
What is bleach used for
a disinfectant, a fabric whitener
