Reactions of halides Flashcards
1
Q
halide ion
A
- reducing agent by losing electrons
- how easy depends on the attraction between the halides nucleus and outer electrons
2
Q
Attraction
A
- gets weaker as you go down the group
- ions get bigger so electrons are further away from the positive nucleus
- extra inner electron shells so there’s a greater shielding effect
3
Q
Reaction with sulphuric acid
A
- KF+H2SO4 arrow KHSO4+HF
- KCl+H2SO4 arrow KHSO4+HCL
- Misty fumes
- F- and Cl- not strong enough reducing agents to reduce sulphuric acid so reaction stops not redox
4
Q
Sulphuric acid and Br
A
- KBr+H2SO4 arrow KHSO4+HBr
- misty fumes
- 2HBr+H2SO4 arrow Br2+SO2+2H2O
- choking fumes and orange fumes
5
Q
KI with H2SO4
A
- KI+H2SO4 arrow KHSO4+HI
- 2HI+H2SO4 arrow I2+SO2+2H2O
- 6HI+SO2 arrow H2S+3I2+2H2O
6
Q
Hydrogen halides
A
- acidic colourless gases
- HCl+H2O arrow H30++Cl-
- NH3+HCl arrow NH4Cl
7
Q
test for halides
A
- add dilute nitric acid to remove ions which may interfere with the reaction
- add silver nitrate solution (AgNO3)
- F=no ppt
- cl=white ppt
- br=cream ppt
- I=yellow ppt
8
Q
test for halides adding ammonia
A
- AgCl=dissolve in dilute ammonia to give colourless solution
- AgBr=ppt remains unchanged in dilute solution however it will dissolve in a concentrated solution giving colourless
- AgI=doesn’t dissolve
