In the experiment of establishing th erelative reactivity of Halogens and Halide
ID: 832222 • Letter: I
Question
In the experiment of establishing th erelative reactivity of Halogens and Halide ions, a student performed the following test on an unknown solution containing one halide ion. When she added acidic 0.1M NaNO2,0.5M HNO3, and CH2Cl2 to a sample of the unknown solution, the CH2Cl2 layer remanied colorless.
What information was revealed by this test? Which halide ion was present in the unknown solution? If an additional test is necessary to confirm or complete you identification, state which test you would use, an what information it would provide.
Explanation / Answer
according to my CRC hand book
(NO2)- & 6 H+ takes 4 e- --> N2O & 3 H2O Eo = 1.297 volts
that is enough to oxidize either bromide or iodide ,
What information was revealed by this test?
no color in the organic layer implies no Br- or I-
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but it is not enough to oxidize chloride
Which halide ion was present in the unknown solution?
likely it is chloride, since we usually don't issue unknown withfluoride
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If an additional test is necessary to confirm or complete your identification, state which test you would use, and what information it would provide.
you add a soution of AgNO3 & slightly acidify with HNO3
chloride will give a white ppt of AgCl
which will then dissociate with concentrated ammonia,
and return when re-acidified with HNO3
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