Prelaboratory Questions And Problems

* 1. Electrochemical studies of the three chloramines show that the mono- is reduced first in an electrochemical cell (i.e., requires the least negative or more positive potential), then the di- and lastly, the trichloramine. The generalized reaction is:

Fill the following table with the stoichiometric coefficients (i.e., n, x, y, z) involved in the three reactions, corresponding to the reduction of one mole of each one of the chloramines.

Chloramine

n

X

y

z

Monochloramine

Dichloramine

Trichloramine

*2. If one mole of chloramine underwent compro-portionation (i.e., the contrary of disproportiona-tion, see Example 2.11 in the companion book) with 1 mole of ammonia in a basic medium to yield 1 mole of hydrazine, N2H4 as the sole nitrogen-containing product plus one mole of hydrochloric acid, which one of the three chloramines was the starting material?

*3. Oxidation of ammonia by chlorine may produce various compounds such as: NO, N2O4, N2H4, N2, N20, NO2 , NO^, and NH2OH.

a) Arrange such compounds according to the oxidation state of the nitrogen contained in each one.

b) Fill-in the following table with the requested formulas and the stoichiometric coefficients that correspond to the theoretical oxidation with elemental chlorine of each nitrogenated species (symbolized as X), as in the generalized equation:

aNH3 + bC\2 + cH20 = X + yCl~ + zH+ (The case of N2O is given as an example).

Oxidation state of NinX

Formula ofX

a

b

c

y

z

Moles of CI2 reduced/mol of ammonia nitrogen

-2

-1

0

+1

N20

2

4

1

8

S

4/2 = 2

+2

+3

+4

+5

0 0

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