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A survey of the methods for the qualitative detection of the halides

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A survey of the methods for the qualitative detection of the halides

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Content A SURVET OF THE METHODS
FOR THE QUALITATIVE
detection oe the halides
A Thesis
Presented to The Department of Chemistry
University of Southern California
In Partial Fulfillment
of the
Requirements for the
Degree of Master of Science
William L, Blalock
June 1939
UMI Number: EP41501
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UMT
' Dtssertati«Psibilisli(jg "
UMI EP41501
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This thesis, written by
William L. Blalock
under the direction of h .^ .f. F a culty Committee,
and a p p ro v e d by a ll its m em bers, has been
presented to and accepted by the C ouncil on
Graduate Study and Research in p a rtia l f u l f i ll
m ent o f the re q u ire m e n ts f o r the degree o f
e® *
Master of Science
Secretary
May 1939
Date.
Dean
Faculty Committee
hairman
(i?7 J
Oil fit31
TABLE OF CONTENTS
CHAPTER PAGE
I. Introduction.......... .1
II. Procedure. ......................3
III. Flouride Detection....... 7
IV. Chloride Detection.•••.....•.•••.•••IS
v. Bromide Detection .............15
VI. Iodide Detection....................21
VTI • Summary................... 26
VIII • Bibliography. ............. 28
CRAP T m 1
INTRODUCTION
The qualitative separation and detection of the anions
is one of the greatest problems of the inorganic chemist.
It is impossible, as yet, to separate the anions into groups
systematically as is possible vfith the cations. Several
chemists, such as Meldrum and Flosdorf^, have attempted
to formulate acceptable systems of anion detection, but
none have proved satisfactory. The reason for this in
ability is that there are no precipitating agents that
successively separate the anions into small groups and
sub-groups. Another important factor is the oxidizing and
reducing action of mahy of the anions in solution. This
factor causes much difficulty in group separation and
often transforms an ion into an entirely different product.
A third factor is the extreme difficulty in the separation
of the individual anions of the same family. The halides
represent the best example of this type of difficulty.
The difference in solubility in ammonium hydroxide of the
silver halides is frequently employed as a means of sep
aration, but this method is not clear cut, and does not
apply to small quantities.
In order to present a series of tests that will be
desirable and definite under all conditions, in this
Meldrum and Flosdorf, Qualitative Analysis1 ' 182-202,
1938.
research, it was attempted to select methods that are
definite under all conditions. The methods investigated
were those recommended "by specialists in the field, and
cover methods that have been used for many years, as well
as the methods proposed within the last decade. The se
lected methods were examined with the following points of
analysis in view, the sensitivity of the test, the inter
ference by other anions, and any modification that would
increase the reliability. Tests that required lengthy
procedures and extensive apparatus were not considered in
detail as such tests do not lend themselves to the usual
qualitative procedure. The bio-chemical determination of
iodine in the blood, suggested by Italo Bellucci^, repre
sents a method of this type. Tests applicable to the
common analytical procedures were considered in detail.
^ Italo Bellucci, "Determination of Iodine in Organic
Substances", Chemical Abstracts, 29, 2114, 1954.
CHAPTER II
THE PROCEDURE
A survey of the work regarding qualitative tests
for halides was made. It was necessary to study the work
which had been done during the last decade, as well as
tests which present day texts offer. The most recent
analytical methods for detecting halides were located in
current magazines and periodicals. The following men are
responsible for a number of such tests: F. Pavelka3,
I.M. Kolthoff and Maurice E. Stansby4, S. Kuhnel Hagen3,
William Brashs, and A.I. Velculescu and d. Cornea7*8,
3 F. Pavelka, "Sensitive Spot Test for Elouride", Chemical
Abstract 23, 3871, 1928.
4 I.M. Kolthoff and Maurice E. Stansby. "Detection and
Estimation of Small Amounts of Elourme", English
Industrial and Chemical Journal, Analytical Edition,
6, 118-20, 1934.
5 s. Kuhnel Bagep. "Detection of Small Quantities of
Plourine", Chemical Abstract 29, 76, 1934.
8 william Brash, "Detection of Small Quantities of Flourine
in The Presence of Other Halides", Chemical Analyst, 58,
686, 1933.
7 A.I. Velculescu and d. Cornea, "Detection of Chloride in
The Presence of Other Halides”, Chemical Abstract 32, 7371,
1938.
8 A.I. Velculescu and J. Cornea, "Detection of Iodides
with Paper Impregnated with Silver Nitrate”, Analytical
Chemistry, 94, 255-257, 1933.
Earl Borgmann 9, E.W. Edwards10, aelim Augusti11, and
A. Basileios1^*1®•
Qualitative text books were investigated in order
to learn about some of the methods used by chemists who
have proposed definite procedures for anion detection.
Among some of the authors investigated were: H.S. Moody14
9 Earl Borgmann, "A Convenient and Cheap Method for The
Detection of Bromine and Iodine", Chemical Abstract, 51
2.121, 1937.
10 j j ’ .W. Edwards, "Determination of Bromine in the Presence
of Other Halides", Analyst 61, 745-749, 1936.
11 Belim Augusti, "Microchemical Detection of Iodides",
Chemical Abstract, 29, 5384, 1935.
12 A. Basileios, "New Method for Detecting Iodides in The
Presence of Chlorates", Chemical Abstract, 29, 1360,
1933.
13 A. Basileios, "New Methods for Detection of Traces of
Iodides in The Presence of Chlorides and Bromides",
Chemical Abstract, 28, 349, 1932.
14 H.S. Moody, "Qualitative Analysis", 1933
Anderson and Bazelhurst 15, Brockman16, Bogness and
Johnson17, Curtman18, Prescott and Johnson19, Ware28,
Engelder21, and Treadwell and nall2^. All of these
authors agree that there is at present no satisfactory
method by which a systematic anion analysis can be made.
So far, definite reagents have been used on the original
unknown solution to precipitate the entire halogen family.
Once the group or family has been precipitated, specific
individual tests are made to detect each individual member.
Instead of using the precipitate, the worker used the
original solution to make specific tests.
Meldrum and Elosdorf23 present a complete systematic
anion analysis in which each anion is separated from all
the others. Tests have proved that this method is not
15 Anderson and nazelhurst, "Qualitative Analysis”, 1933.
18 Brockman, "Qualitative Analysis”, 1930.
17 ilogness and Johnson, "Qualitative analysis", 1939.
18 Curtman, "Qualitative Analysis", 1931.
19 Prescott and Johnson, "Qualitative Analysis", 1933.
20 Ware, "Qualitative Analysis", 19E8.
21 Engelder, "Semi-micro Qualitative Analysis", 1936.
22 Treadwell and Ball, "Qualitative Analysis", 193S.
28 Meldrum and Plosdorf, "Qualitative Analysis”, 1936.
definite for many of the anions, especially the halides
and the anions which do not lend themselves to the form
ation of precipitates.
The first part of the research consisted in
following the methods according to the suggested procedures.
The possibilities of the tests therefore were more
evident. The minimum quantity of the anion that might be
detected by each method was then determined. The inter
ference of other anions was then investigated by including
these anions with the anion under investigation and
determining the ratio of interference. The greatest
difficulty lay in the removal of other anions of the
halogen group when they were present. This was done by
following the best method adapted to the anion under
investigation. The remainder of the research consisted
of an investigation of possible changes in the proposed
tests that would increase the value of the procedure.
CHAPTER III
FLOURIDE DETECTION
The harmful effect of traces of flourine upon the
teeth, has caused an increasing interest in the occuranee
of traces of this element. This new interest has demanded
a simple, specific, and sensitive test for the detection
and estimation of this element.
The method suggested "by ^-olthoff and Stanshy2^,
represents one of the newer attempts toward more specific
detection. The reagent used for the detection was made
with the following reagents:
Basic ErOCl ..................... 0.16g.
Concentrated HCi .......... .lQO.cc.
Water ......................... 100• cc.
P u r p u r m « . . . 9 « g «
alcohol........ .....................30. cc.
Water to make the total one liter.
The flouride ion, which also must he in a strong
acid solution, causes the color of the reagent to change
from pink to yellow*
Investigations found the amount of flouride ion detect
able was 0.005 milligrams in solutions containing no
interfering ions. Sulfates interfere when present in
quantities over 0.001 milJLigrams, but may oe removed
P4-
I.M. Kolthoff and Maurice E. Stansby, "Industrial and
Engineering Chemistry”, Analytical Edition, 6, 118-121,
1934*
8
satisfactorily by the addition of barium chloride to the
acid solution. Phosphates were found to interfere, causing
the solution to become cloudy and making it impossible to
detect the color change. Oxidizing agents destroy the
color of the reagent due to the liberation of chlorine
from the reagent. Nitrated bleach the color after a
period of time, but since the action of the flouride is
immediate, no harm is derived by having nitrates present.
A modification of the test, as suggested by the
authors, was found to be satisfactory in the presence of
any of the other anions. The test solution was evaporated
to dryness and powdered silica added to the residue.
Concentrated sulfuric acid was then added to the mixture
and was heated cautiously. The silicon tetraflouride which
was formed in the presence of flourides changed the color
of the reagent from pink to yellow immediately. This
method is one of the best.available for the detection of
moderately small amounts of flourine. The regular pro
cedure may be followed if there are no interfering anions,
however if there is any doubt as to the reaction, the
modification may be used satisfactorily.
A good qualitative test for flourides has been
suggested by Tananaev and Savchenko**5. The procedure
25
I.M. Tananaev and u-.S. Savchenko, "Journal of Applied
chemistry", 7, 229-251, 1934.
suggests that the solution of flouride ions be heated and
then made alkaline with sodium hydroxide. Silver nitrate
is added to this solution until the precipitation is
complete. The filtrate on filtering, is added to a
solution of calcium nitrate which must be free from
chloride ions. A white milky precipitate forms in a few
seconds whenever the flouride ion is present.
This method was found to be sensitive for 0.001
milligrams of the flouride ion. Any of the anions which
form insoluble calcium salts were found to interfere,
Ions that are colored in solutions prevent the detection
of the fine white precipitate. All interference from the
anions may be removed as follows: Evaporate the solution
to dryness and add a few drips of concentrated sulfuric
acid to the residue. Hydrogen flouride is generated in
the presence of flouride ions when the mixture is heated.
If the hydrogen flouride vapors are caught in a solution
of iNi/2 sodium hydroxide and the solution treated in the
original method, satisfactory results are obtained without
any interference. This modification is not as sensitive
as is the regular procedure, in which 0.01 milligram of
flouride can be detected, but the knowledge that no anions
interfere places this modification above the original in
reliability.
The uneven flow of concentrated sulfuric acid over
10
glass that has "been etched by hydrogen flouride has been
proposed as a method of detecting small quantities of the
flouride ion26.
This procedure was found to be accurate in the presence
of 0101 milligram of the flouride ion. The syrupy sulfuric
acid follows the lines of the slightly etched glass, mak
ing possible the detection of etching when the eye is
unable to see any traces of markings. The same type of
identification can be made by washing the glass which has
been treated with the reagent and allowing it to dry.
After the glass has dried, it is very easy to follow the -
slightly etched lines as these etchings appear as thin
white lines upon the clear glass. Dither method may be
used with confirming results for the flouride ion.
F. Pavelka2?, depends upon the fact that flourides
destroy the color of a zirconium alizarin lake. The
reagent was prepared with the following materials:
Basic £rOClg ........... lg.
Water.................... lOcc
Saturated alcoholic solution of alizarin ..20cc.
Acetic acid.................. 50% solution
The alizarin solution is added to the solution of
26 S. Kuhnel Hagen, C.A., 29, 5384, 1935.
27 F. Palvelka, t s Sensitive Spot Test for Flourine", C.A.,
23, 3871, 1928.
11
the basic zirconium chloride producing a dark red color
ation. Filter paper or spot-reaetion paper is moistened
with this solution and then is allowed to dry. The paper
is then remoistened with the acetic acid solution which
does not cause any color change. The color bleaches
immediately if flouride solution is dropped on the paper.
A small a quantity as 0.005 mg. of flouride ion may
be successfully detected by this method. However sulfates,
oxalates, and phosphates interfere with the detection as
the reaction of these anions upon the reagent is identical
with the reaction of the flouride. The other halides were
found to give no interference, but the colored ions inter
fered with detection of the bleaching effect. Interference
by any of the ions may be removed by the following method:
evaporate the solution to dryness and generate hydrogen
flouride, and hold the moistened reaction paper in the
escaping vapors. The reagent bleaches immediately when
ever flourides are in the unknown. The sensitivity of this
test is 0.01 mg. of flouride ion.
CHAPTER IV
CHLORIDE DETECTION
One of the latest methods for chloride detection has
OD
"been proposed "by Ifilliam Brash. ° Silver nitrate is added
to a solution of the anions until precipitation is com
plete. The solution is then filtered and the residue is
washed with water until free from soluble silver salts.
The precipitate is then suspended in water and is mixed
with a few drops of potassium ferricyanide solution. To
this mixture approximately five drops of ammonium hydroxide
is added which dissolves enough of the silver chloride to
give a brownish precipitate of Silver ferricyanide. The
silver ferricyanide is much less soluble in ammonium
hydroxide than is silver chloride.
Success with this method demands that the solution
of potassium ferricyanide must be freshly prepared.
Traces of sulfides, thiosulfates, and ferrocyanides inter
fered definitely, while arsenites and arsenates did not
interfere in quantities less than 0.001 milligram. If
more ammonium hydroxide is added after the formation of
the brown precipitate, the arsenic precipitates dissolve,
leaving the brown residue of silver ferricyanide. This
28 William Brash, "Detection of chlorides in The Presence
of ether Halides", The Analyst, 58, 686, 1933.
13
method is a good pocedure in the presence of the hhlide
ions but can not be used with definite results in the
presence of any of the interfering anions mentioned.
Luigi Martini^ states that both flourine and
iodine interfere with the chromyl chloride test for
chlorine.
Investigations indicate little ground for this
statement. Research tests were made for chloride in
the presence of excess,flouride and iodide ions, and
flouride was found to give no interference of any kind,
while the iodide was found to give only a coloration to
the solution. Neither anion prevented the formation of
lead chromate through the reaction of the chloride ion,
and neither anion was found to give a precipitate when
used alone. This method is simple, quick, and conclusive
in the presence of 5 mg. of chloride ion.
The reactions envolved are:
KgCrgO?* 4NaCl 4 6H2804-» 20r02Cl242i£HS0444RaHS04f 5HgO
CrOgClg + 4RH40H -MNH4)2Cr04^- 2RH4CI + 2H20
(HH4 )2Cr04^ Pb (CaE3U2)2 PbCr04 4- 2RH4C2H302
CCA
A method suggested by Velculescu and Cornea
requires a mixture of one part 40^ formaldehyde to ten
30
A.I. Velculescu, ’ ’Detection of Chloride in The Presence
of 0-6her Halides’ 1, C.A. 32, 7371, 1938.
29 Luigi Martini, C.A, 30, 4115, 1935.
14
parts in/10 sodium hydroxide as a reagent. When this
reagent is added to a mixture of the silver halides, only
silver chloride is reduced.
This method is very sililar to that employing
ammonium hydroxide to dissolve the silver chloride, and
has approximately the same value. Cyanides, thiocyanides,
sulfates, thiosulfates, ferro and ferri-cyanides defi
nitely interfere, regardless of the amounts present.
Satisfactory results may he obtained in the presence of
interfering ions by the following modification: add
sodium hydroxide and formaldehyde to the mixture, then,
filter, citric acid is then added to the filtrate until
it is distinctly acid. Add silver nitrate to the so
lution and note a white precipitate which confirms chloride.
The sensitivity of the test is not great, as one milli
gram of chloride ion is the smallest amount that can be
detected.
CHAPTER V
BROMIDE DETECTION
F.W. Edwards3- 1 - presents a simple method for the
detection of the bromide ion in the presence of chlorides.
The suggested procedure treats the bromide solution with
2 cc. of normal potassium permanganate solution and 5 cc
of phosphoric acid diluted to five times its volumn with
water. The liberated bromine is distilled into a sol
ution of one per cent potassium iodide and the liberated
iodine is titrated with bi/5 sodium thiosulfate. When
iodides are present in the original solution, a larger
amount of permanganate solution must be added in the ratio
of 9 cc. of permanganate solution to 100 mg. of iodide.
The prepared solution is allowed to stand for ten minutes,
then air is aspirated through the mixture for 50 minutes.
The iodide ion is oxidized to the iodate by this procedure.
The procedure for removing the iodide ion was found
to be unsatisfactory. After air had been aspirated
through the solution for one hour, the solution still gave
a strong test for the iodidd ion. The iodide may be re
moved satisfactorily by the following procedure: boil the
solution with a three per cent solution of hydrogen peroxide
31 F.W. Edwards, "Detection of Bromide in The Presence of
Other Halides”, The Analyst, 61, 743-749, 1956.
16
and extract the iodine with carbon tetrachloride. The
original procedure may then he used to test for the
bromide ion. Chlorides and all other ions do not inter
fere with the procedure. The sensitivity of the method is
1 mg. of bromide ion when iodides are not present and 3 mg.
when iodides are present.
a.-desirable method has been proposed by Gurtman and
Schneidderman32 for the detection of the bromide ion in
the presence of thiocyanides, iodides, and chlorides. The
test solution is treated with silver nitrate to precipi
tate the ions. After filtration, the residue is washed
until it is free from soluble silver salts. A portion of
the residue is treated with five drops of sodium chloride.
This is heated and then cooled. A drop of concentrated
hydrochloric acid and five drops of ferric chloride are
added to test for thiocyanide. If thioeyanide is present,
the remainder of the residue is heated in a casserole until
all the thiocyanide is decomposed. .Dilute sulfuric acid
and two grams of zinc shot are added to the residue and
the solution is stirred for ten minutes. The remainder
of the zinc and the reduced silver is filtered from the
32 l.J. Gurtman, and H. Schneidderman, "Detection of
, Bromine and Its Application to the systematic
Analysis of Mixtures of Thiocyanides, Iodides and
Chlorides". C.A. 29, 2476, 1935.
17
solution and hydrogen peroxide is added to liberate the
iodine. The iodine is extracted with carbon tetrachloride
and the rest of the solution is treated with 5 cc. of
concentrated nitric acid. The solution is heated and the
bromine is extracted.
This procedure was found to be satisfactory in the
presence of all the anions. The only difficulty occurs
in the complete removal of the iodide. It was found
necessary to treat the solution, after the first extraction
had been made, with sodium nitrite and a few drops of
sulphuric acid which insures complete removal of the iodide.
The chloride ion may be tested for in the filtrate by
adding silver nitrate. A white precipitate indicates
and confirms the presence of chlorides. There is no
interference by any of the other anions in this procedure.
The sensitivity of the test is 0.01 mg of iodide, 0.1 mg.
of bromide and 0.1 mg. of chloride.
Aarl Borgmann33 suggests a reagent for bromine and
iodine. A few drops of concentrated hydrogen peroxide
or its equivalent of the three per cent solution and 2-3
cc. of dilute hydrochloric acid are used for the test.
33 iiarl Borgmann, "A Convenient and Cheap Method for The
Detection of Bromine and iodine”. CjiA., 31, 2121, 1937.
18
This method does not propose that the anions be
separated, but claims satisfactory results may be had
through the identification of the color of the carbon
tetrachloride used for extraction. This procedure is
noticably weak in the detection of the bromide ion, and
especially so if the concentration of the iodide is
equal to or greater than the concentration of the bromide
ion.
The reagent acts more quickly upon the iodide than
the bromide, producing a type of reaction that may omit
the detection of the bromide entirely. However, the
procedure was found to be more conclusive if the iodine
is extracted soon after the reagent has been added, then
test the bromine in the filtrate by adding a few drops of
concentrated nitric acid. .Better results were found by
this modified method, but the sensitivity is not great.
The least possible amount of bromine detected was 0,1 mg,
Another method has been proposed by Ziombray and
Plook34 which makes use of the color changes of bromo-
phenol blue, bromocresol green, and ehlorophenol red. The
The method was found to provide no possible means by which
the chloride and bromide ions might be separated and
identified. .Each ion reacts with the reagent in identically
34
jl.V. Ziombray and L. Plook, "Determination of Mercurous ~
Mercury, Chloride and bromide", CM* 28, 990, 1933.
19
the same way, thus making it impossible to detect which
ion is in the unknown solution.
nermann Eichler35 has suggested a method which
detects the presence of bromides or chlorides by the
disappearance of the characteristic fluoresence of re-
sorusin in the presence of alkali or ammonium carbonates.
The reaction does not distinguish the difference
between the two ions, and it is not satisfactory for
qualitative uses.
Xn this research, a combination of several of the
proposed methods has been used in developing a procedure
for bromide detection. Hydrogen peroxide is added to
a solution containing the bromide and iodide ions; the
solution is heated and carbon tetrachloride is used to
test iodine. This extraction is made with only a portion
of the solution. To the remainder of the solution, B/XO
potassium permanganate is added until the solution remains
a slight purple color. The solution is filtered to remove
the precipitated manganese oxides. A few drops of con
centrated nitric acid are then added and the solution is
warmed again. The bromine is extracted with carbon tetra
chloride. This method is satisfactory in the presence of
all other anions, but is not sensitive for quantities less
Hermann Eichler, "Detection of Chloride and Bromide”.
C.A., 29, 1359, 1934.
than one milligram of bromide or iodide.
UHAPTER VI
IODIDE DETECTION
The presence of iodine in mineral waters, foods
*
and chemical compounds necessitates methods for de
tection and estimation which are definite and reliable.
Many methods which have been suggested meet the require
ments of the analytical chemist.
A. Basileios^6 has proposed a procedure which is
very sensitive and is suitable for detecting small
quantities of iodine in large excesses of chlorates.
The procedure consists of cautiously shaking 10 cc. of
of a neutralized solution of the iodide with 2 cc. of a
2° / o solution of iodine in chloroform, avoiding fine
dispersion of the latter, a few drops of a Vfo starch
solution is added and the cylinder is rotated gently.
The aqueous layer turns blue in the presence of iodides,
and the intensity of the blue color is proportional to
the quantity of iodine present. Estimations of the
amount of iodine present can then be made colormetrically.
In this investigation, this procedure was found
to be accurate in the presence of any of the other halide
ions. The sensitivity, which was suggested to be
1:750,000, was found to be considerably less. Only 0.001 mg.
a , Basileios, "New Method for Detecting Iodides in The
Presence of chlorates”, C.A., 29, 1935, pp. 1360.
22
of the iodide ion could be identified definitely. Under
most conditions, there is no interference by any of the
other anions.
Two spot tests for detecting the iodide ion has
' * 5 7
been suggested by Selim Augusti. The first demands
an ammonical solution of mercury amnio-nitrate as the
reagent, which is composed of:
Hg2(N°3)2 .................... 10 g.
HN03 (Concentrated)............. .5 cc.
Water. .......................50 cc.
HH^OH (Concentrated).............60 cc.
Moisten the spot reaction paper with the reagent and
add a drop of the test solution. Iodides precipitate
a bright yellow spot which changes to orange color as
the paper dries.
The sensitivity of this test is 0.015 gr. of
iodide ion. There is definite interference when the
sulfide ion is present. The black spot precipitated
by the sulfide ion, obscures any possibility of the
yellow color. This interference occured whenever there
was a trace of the sulfide ion present. Chromates
interfered to a certain extent, giving a darker yellow
spot which was not increased in intensity by drying
37
Selim Augusti, "Microchemical Detection of Iodide
Ions", C.A., 29, 5384, 1935.
However if a known iodide test is made at the same time,
it is possible to detect the difference between the
chromate and the iodide-ions• The depth of the orange
color of the iodide after the spot paper has dried,
suggests a possible method for estimating the amounts of
iodide present in a sample.
The second method proposed by Selim Augusti uses
a reagent composed of .a dilute solution of sodium hypo-
ehlorate and a Vp> solution of magnesium sulfate in equal
quantities. Iodides form a brown spot upon spot reaction
paper when this reagent is present.
This test proved less sensitive than the mercury
amnionitrate reation. It was found that there is no
interference by sulfide ions in this reaction, but the
chromates interfere in all possible ratios. The sensi
tivity of the test was found to be only 0.1 mg. of the
iodide ion. Hone of the other anions interfere with
this reaction.
Velculescu and Cornea*^8 have proposed a method of
iodide detection on the microchemical scale by impregna
ting filter paper with a 0.1^> solution of silver nitrate.
This method is not bo be recommended for solutions
containing ions which give colored precipitates with
silver nitrate. All traces of silver precipitates
38
A.I. Velculescu and J. Cornea, "Detection of Iodides
with Paper Impregnated with Silver nitrate", C.A. 28,
70, 1933.
24
definitely interfere with this test making it impossible
to definitely detect any particular ion. Sulfides, thio-
sulfates, chromates, arsenates, arsenites, and ferri-
cyanides definitely interfere in any amounts. The
sensitivity of the test in the absence of interference is
0.001 mg. of iodide ion.
Probably the most sensitive and reliable procedure
for the detection of the iodide ion has been suggested
by Basileios . This method consists of adding two drops
of a freshly prepared 1% starch solution to 5 ec. of the
test solution. Three drops of 3.5% hydrochloric acid
and 1 cc. of iodine solution are added. The iodine solution
is prepared by dissolving 0.1 gram of iodine in 10 cc. of
6iM sodium hydroxide and then the solution is diluted to
100 cc. On addition of the iodine solution to the pre
pared test solution, the whole turns blue whenever iodides
are present.
This method was found to be very sensitive, 0.000025
mg. of the iodide ion can be detected definitely. There is
no interference by any of the other ions. The only part
of the procedure that requires special attention is the
amounts of the reagents added. If too much hydrochloric
39 A. Basileios, "Detection of Traces of Iodides in The
Presente of Bromides and Chlorides", C.A., 28, 4006,
1932.
25
acid is added, the "blue color appears even in the absence
of the iodide ion, due to the reduction of the iodate
formed in the sodium hydroxide solution. ‘ Phis was found
to he the best test proposed for iodides.
■r
26
CHAPTER VII
SUMMARY AKD CONCLUSIONS
It has been shown that the great number of newly-
proposed methods for halide detection, clearly indicate
that there is much to be accomplished in this field of
experimentation, especially in the field of suitable
methods for the detection of chlorides and bromides in
the presence of the other halides.
In' studying methods for the detedtion of flouride
in the presence of other ions^ it has been shown that
the method of iLolthoff and Stansby, based on the color
change of an acid solution of basic zirconium chloride
and purpurin, yields satisfactory results whenever the
test is performed with silicon tetraflouride generated
from the test solution.
The alizarin-basic zirconium chloride method of
Pavelka has been found to give good results in the
presence of any of the ions whenever the reaction paper
is held in vapors containing hydrogen flouride.
The possibility of using the etching test for the
detection of flouride has been shown to give clear
results by using sulfuric acid as a means of detecting
the etching of the glass.
The ehromyl chloride test was found to give favorable
27
results in the presence of any of the ions. It was also
found that the flouride and iodide ions do not interfere
with the chloride detection by this reaction.
In a survey of the methods used for the detection
of the bromide ion, the procedure of Curtman and Schneidder-
iaan, was, found to yield reliable results. They used
nitric acid to liberate the bromine which was then ex
tracted with carbon tetrachloride,
A method, consisting of several tests from other
authors, has been developed and is found to be definite
fn the presence of all the ions, for bromide detection.
The procedure consists of removing the iodide with
hydrogen peroxide and potassium permanganate and then
detecting the bromide in the filtrate with a few drops of
nitric acid.
The two methods of iodide detection proposed by
Basileios were shown by investigation to be both reliable
and sensitive. The first method used a solution of
iodine in chloroform and the second used a solution of
iodine in sodium peroxide as the principle reagents.
Both procedures may be used with the greatest of con
fidence.
BIBLIOGRAPHY
Anderson and Hazelhurst, "Qualitative Analysis^ Hew
York: John Wiley & Sons, 1933.
Brockman, wQualitative Analysis”. Hew York: Ginn
and company, 1930.
Curtman, ”Qualitative Analysis” . Hew York: The
Macmillan Company, 1934. -
Engelder, "Semi-micro Qualitative Analysis”. Hew York
John Wiley and Sons, 1936.
Hogness and Johnson, "Qualitative Analysis”. Hew York,
H. Holt and Company, 1937.
Mel drum and Elosdorf, "Qualitative Analysis”. Hew York,
American Book Company, 1938.
H.S. Moody, "Qualitative Analysis”. London, William
Heinemann Ltd., 1937.
Prescott and Johnson, 1 1 Qualitative Analysis”. Hew York,
D. Yan Hordstrand:and company, 1932.'
Treadwell and Hall, "Qualitative Analysis”. Hew York,
John ?\filey and Sons, 1937. • ■ ' »
Ware, "Qualitative Analysis”. Hew York, John Wiley and
Sons, 1928.
Chemical Abstracts, 23, 28, 29, 30, 31, 32, 33.
Industrial and Engineering Chemistry, Analytical Edition,
6, 1934.
Journal of Applied Chemistry, 7, 1934.
The Analyst, 58, 61, 1936.

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Creator Blalock, W. L (author)

Core Title A survey of the methods for the qualitative detection of the halides

Degree Master of Science

Degree Program Chemistry

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag chemistry, inorganic,OAI-PMH Harvest

Language English

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Advisor Smith, Frank (committee chair), [illegible] (committee member), Clark, L.T. (committee member)

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