Halogens Flashcards
What colour is F2 at room temp?
Yellow gas
What colour is Cl2 at room temp?
Yellow-green gas
What colour is Br2 at room temp?
Red-Brown Liquid
What colour is I2 at room temp?
Grey-black solid (violet/purple vapour heated)
What is sol of Cl2 like in water?
Soluble forming a green/ col sol
What is sol of Cl2 like in hexane?
Soluble forming a col sol
What is sol of Br2 like in water?
Soluble forming yellow/orange/brown sol
What is sol of Br2 like in hexane?
Soluble forming a red sol
What is sol of I2 like in water?
Virtually insoluble- but any sol formed is yellow/brown
What is sol of I2 like in hexane?
Soluble forming a violet/purple sol
What is disproportionation?
Where one species oxidised and reduced in the same r
State the equ of NaOh in Cl- cold and dilute:
2NAOH+CL2-> NACL+NACLO+H20
State the equ of NaOh in Cl- HOT AND CONC:
3CL2+6NAOH-> 5NACL+ NACLO3+ 3H2O
What is formed in both r with NaOh sol?
Yellow and green gas dis to form colourless sol
Why does ox ability of halogens decrease down group?
B/c atomic no increases
Oxidising agent gains e and becomes reduced
Halogen atom gains e in outer en level to complete en level
Why is F2 easier oxidised than Cl2?
Completes en level closer to nucleus than e. than completes outer en level in CL2
E. that F2 gains has stronger attr to nucleus b/c closer to nucleus than for a Cl2 atom
E gained by F2 not subject to as much shielding by inner e. b/c fewer e between e gained and nucleus
Why does the reducing ability of halides increase down group?
Increases as atomic number increases
Reducing agent loses e and becomes oxidised- donates e
Halide ions loses e from outer en level
Why is I2 more readily reduced than Br2?
E. lost by I- ion comes from en level further from e than would be lost by Br- ion
E that I- ion loses has weaker attr to nucleus b/c further from nucl compared with other halide ions
E lost by I- ion is subj to greater shielding by inner e than other halide ions b/c more e between e lost and nucleus
What are the obs of equ:
NaF + H2SO4-> NaHSO4 + HF
Misty fumes
Heat released
Gas produced
S dis.
Pungent smell (HF)
What are the obs of equ:
NaCl + H2SO4-> NaHSO4 + HCl
Misty fumes (HCl)
Heat rel
Gas prod
S dis
Pungent smell (HCl)
What are the obs for equs:
NaBr+H2SO4-> NaHSO4 + HBr
2HBr + H2SO4-> Br2+SO2+2H2O
Misty fumes (HBr)
Heat released
Gas produced
S dis
Red- brown vapour
Pungent smell (HBr/ SO2/ Br2)
What are the obs of sodium iodide with sulfuric acid?
Misty fumes
Heat released
Gas produced’
S dis
Purple vapour and grey-black s (I2)
Pungent smell (HI, SO2, I2)
Rotten eggs smell (H2S)
Yellow s (S)
How do you test for halide ion Cl-?
Test using glass rod dipped in conc NH3 sol- white smoke given off (HCl)
How do you test for Br- ions?
Gives Br2 vapour with conc H2SO4 acid-> red-brown fumes
