The Students' Guide in Quantitative Analysis - Free Ebooks Library

32
QUANTITATIVE ANALYSIS.
crucible, ignite cautiously to low redness, and weigh as
CaSO,. Compare Fres., § 103, 3, b, a.
Note 7.— If care has been taken to avoid undue excess of
NH^Cl in the preceding steps, the magnesium may be
thrown down in "/^///w^^ 6-" immediately. Otherwise the
NI'I^CI must be expelled as follows : Concentrate the liquid,
add 3 grms. of HNO3 for every grm. of NH^Cl supposed
to be in the solution, warm gently (60° C.) and eventually
heat to boiling.
Concentrate '' Filtrate c" add NM^HO and NaJdPO^
and proceed as in Analysis 2. B. See Fres,, § 104, 2, and
% 7A-
:
Notes on the Decomposition of NH^Cl by IINO3 in solu-
tion. Comptes Rendus, October 13, 1851 (Maumene).
J. Lawrence Smith in American Chemist, Vol. Ill, p. 201.
Also Am. Jour. Sci. (2), Vol. 15, note, page 240, which is as
follows: "The character of the decomposition which takes
place is somewhat curious and unexpected : it was first
supposed that equal volumes of CI, N,0, and N were given
off, but it is shown that nearly all the NH,HO, with its
equivalent of HNO^, is converted into N,0, the liberated
HCl mixing with the excess of HNO3. A little of the
ISrH^Cl-}-HN03 does hot undergo the decomposition first
supposed, and in this way only can the small amounts of N
and CI be accounted for."
" Some nitrous or hyper-nitrous
acid forms during the whole process if cone. HNO3 is used
little or none if dilute HNO3."
The action of NH.NOj on NH.Cl is theoretically as
folio Hows
2{NH,N03;H-NH,C1=5N+C1+6H,0.