PHYSICOCHEMICAL PROPERTIES OF CALCIUM ABSENATES

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600260576-4
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 8
• Document Creation Date: December 22, 2016
• Document Release Date: August 4, 2011
• Sequence Number: 576
• Publication Date: November 10, 1949
• Content Type: REPORT

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t;iAtj0?1C;A1 ION C0$FIDEii'I'IAL l:? ?~, ,_,; f 6"s~~ir e
CENTRAL INTELLIGENCE AGENCY REPORT
INFORMATION FROM
.STS rn K l()
FOREIGN DOCUtntN i b L.li Div onG ? - ? -
COUNTRY usaR
SUBJECT Scientific, - LLaeti-,idea
HOW
PUBLISHED 14cnthlipariodioal
WHERE
PUBLISHED k4cs::ow
DATE
LANGUAGE Russian
or TNl DNITED #TAll$ NITNIN r ... ._--
4, {. 0.. f I AND 31. A{ A1155013. IT{ TARN{^1{SION Of TMN IITILOT:ON
OI )Yf CONT]NTf 1T ANT NANMIIN TO AN YNADTNO{I+fO P/N#ON IL IAU?
NI{1TND {T W11. NIIIIODDCTION OT THIS IDIN If- ..0111NI100.
SOURCE
DATE OF
INFORMATION 1949
THIS IS UNEVALUATED INFORMATION
PHTSICOcM410AL PRCPEEfPIFS OF CLLCIUM ARMATPS
_ -..a N T Tw]InlTk~na
Sci Inst of Fertilixn7a
end Insectofungicides
L iguras are appended]
Inluatrial calcium arsenate used as an enterotropic insecticide is a basic
calcium salt of orthoaraenic acid. The exact eompo?it1on end -ktrilcture of 3?~
industrial sampler is unknown. The molar ratio 00 ; As22O55 veri.s from 3?.1 to
in variora samples. While conducting pinloioochemical studies in the field of
calcium arsenates, we developed a method for obtaining neutral caul basic calcium
salts of ortboarsenlo acid. As a s+arting agent we used arsenic acid and a
calcium hydroxide solution instead of suspensions. With the use of the calcium
hydroxide solution, ve obtained b.- p'.e farm the following cr7atallic compounds:
4CaO?Aa2O5 5A2O, peuzahydrate of tetra.caicium-arsenate and 3CaO?As205'10B20,
deeahydrate of tricaleium-arsenati. The first is made up of rectangular prisms
and the second, of rhombic flakes.
While preparing the individual compounds and also in studying their chemic6l
properties, we noted that their water suspensions have quite different properties.
Thus, a suspension of 4CaO?Aa205.5H20 in the ratio of 0.1 gm of the substance to
25 ml of voter hsean alkaline reaction (pH9.6); and in the titration of such a
suspension with a 0.02 N HCl solution in the p,-eseace I..L phenolphthalein, the
alkaline coloring of the indicator increased continuously. Complete neutralization
took piece only when about 12 - 15 percent of the cniciimi oxide was titrated back
by the acid. On the other hand, a water suspension of a solid solution of
calcium hydroxide in dihyarate of triealcium-arsenate with molar retic CaO : Aop04
equal to 3.8 under the very same conditions has pH 8.6, and the phenolphthalein
coloring disappears after titrating back only 1 - 2 percent CaO.
Inir IIniEll Iat
.50X1-HUM
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Water suapensio,ie of 30a:%?Aa205.10H,220 and 3Ca0?Aa20 '2H20 also have different
properties. Suspensions of 30a0?As205'1.OH2O have pH 9.1. In titrating a suEpen-
sion with 0.02 N HC1 solution in the presence of phenolphthalein. neutralization
took place oL:y after 5 - 6 percent of CaO was titrated back by the acid. Suspen-
sione of CaO?Az205.2H_,O have 8.3, and neutralization of the suspension occurred
o
2eduee the solid phase to a composition of a roximate 2 CaO'As 0 y
pp ly 5 (calczzl8ted).
Suspensions of 3OaO?Aa205'21e20 or solid solutions have pH 8.3 -- 8.6,5and therefore
the neutralization takes place after the addition of very small quantities of the
0.02 N H!".1 solution.
f
s one roam Ca0 As205?5H2O or 3caa?Aa205?10H20 yield a neutral reaction with
phenophthelein only after adding 0.02 : HC1 solution in tha amount Macassar t
hour . The results shove that the difference in the behavior of water suspensions
of calcium arsenate samples is not chance, but follows a definite pattern: suspen-
i
4
an& 6n17 I percent of CaO in 24 hout,a. In the titration of suspensions of 3Ca0?
A62O '2H 0 and eoz.id Solutions, the time cf complete neutralization Wag 70 - 80
The reaulta of titratiog water suspensions of various samples with a O.O^
NHC1 solution and the pH determinations for the solutions are shown in Table L.
These o3servations were madeon numerous samples, the chase composition of
which had been previously investigated.
Compositions and "Solubility" Curves
It is possible that this difference in the properties of the ^cmpo,a,u? should
be ascribed to the structure of the compounds crystal lattice. We checked the
"solubility" of the compouta having different pH values (solubility is set in
al,ntra finnw~ e, abacluta ~c u~i l~tj - i ro .. - -
- bair.C cuii~J iCtf95 ou/.
The testa were conducted for pH values ranging from 7.5 to 10 by the follo-r-
ing Method: A weighed portion of the sample (0.1 g) was placed in a cylindrical
vessel (capacity - 100 ml). Then 50 ml of a standard buffer solution were poured
in the vessel. i'he solubility of each sample was determined at four points with
pH values equal to 7.3, 8.2, 9.2, and 10. The vessels were placed in a water
thermostat in which they were rotated continuously for 6 hours. Then the vessels
were left undisturbed for 14 hours and again rotated for 4 hours. The thermostat
temperature vas-25 degrees. The pH values and the Ps1Ogg content were determined
in filtrates by the iodometric method. The Solubility free eup'ressed mg-equivalents
of As20.g per liter. The pH value of the filtrates was determined by the colort-
metric Sni.+.cator method.
The buffar solution wee prepared from boric acid, borax, KOH, and KCl. We
intentionally refrained from using phosphoric acid welts, remembering previous
references to excellent results for solubility obtained in the region of high
PH values due to the low solubility of calcium phosphate which forms under these
conditions.
Table 1. Rasult9 of Titrating Suspensions from 0.1 g of the Substance in 2,1 ml
of H2O in the Presence of Phanophthelein.
No of
Samples
CaO/As2O5 by
Chemical Analysis Chemical Formula
Titration of Suspensions
With Phenophthelein
Initial Value
of Suspensions,
pH Valve
M_
--
~-~
0.02 N HCL Sol-
ution (ml)
ceo
(%)
8.7
,
4.o f
25.3
14.2
9.6
~0
4.ct
23.2
13.0
9.6
65
4.0
4Cao?As2n5.5H2o
25.6
14.3
66
6
hjo
)
20.75
11.6
9.6
7
4.o
21.1
11.8
9,6
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No of CaO/As2O5 by
Samples Chemical Analysis
(COIL tai)
Titration of Cuspensione Initial Value
Chemical Formula With Pbonophthelein of Suspensions'
pH Value
0.02 N HC1 sol-
ution (ml)
CaO
W
48
3.0
3Ca0?Ae205.1OH20
9.0
32
3.0
30a0'As205'101120
10.0
5;6
123
3.0
3Ca6.Ae205' PH20
0.7
0,4
53
3.
1.0
0,56
64
3.6
2.5
1.4
63
3.5
2.4
1.3
57
3.8
3.1
1,74
46'
3.7
Solid solutions
1.0
0.56
112
3.3
1.5
0.84
3.7
2.3
1.29
114
3,5
1.12
No of
Samples
48
50
87
65
69
123
46
112
53
63
74
57
Determining the "Solubility" of Calcium Arsenate Samples
Composition
"holubility" in Buffer Media in Mg-equlvalant8
or +18205 per Li tar
eq mg eq eq eq
ph .,0205
"b2" 5 P" A82u5 I'd B205
3Ca0?Aa205.10H20
7.5
13.0
8.2
8.2
9.3
4,7
4.1
30a0?Aa205.10ii20
7.5
13?
4Ca0?Ae205.5H20
7.8
12.5
8.2
lo.6
9.4
5.3
10
2.7
.4Ca0?As205.5H20
7.9
13.4
8.2
10.6
9.3
5.
10
3.4
iCa0 a205.5H20
7.9
12.6
8.2
11.0
9.4
5.9
to
3.5
3ba0`As205'2H20
7.4
6.4
8.1
31.4
9.2
2.3
10
1.6
Ce0: A0205c3. 2'\
7.5
.4.1
8.1
1.85
9.3
0.9
10
0.85
CaO:Ss205-:3.2
7.5
3.9
8.2
2.2
9.4
0.9
l0
0.77
CaO:As205 3.4
7.5
3.2
8.1
1.2
9.2
1.1
o.65
CaO:Ac205z3.53
( solutions
7.5
3.8
8.1
2.3
9.2
0.8
10
0.4
Cao:As205_3.6
7.5
3.4
8.1
1.0
9.2
0.3
10
0.3
Cao:Aa205,3.8
7.5
3.3
8.2
1.2
9.2
0.3
10
C.1
CONFIDENTIAT.
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The results of deter inirg the "solubility" of calcium arsenate samples are
presented in Table 2 and Figure 1.
As seen from the results, the "solubility" curves for 4CaO'As 0gg5H,~O and
3CaO'As 055 10H20 are very close and are much higher than the "eolngiSitys' curves
for 3Ca0'Aa205 2 0 ant are solid Solutions. The solubility of the latter is low
and hah a tendency to decrease with increase in the molar ratio CaO/As205 in the
solid solution.
The Connection of the Chemical Pneerties and'Solubilit? Curves With the Strccture
c Calcium Solt of OrtheArRenic Amid.
It is possible to separate the compounds under study into two types on the
basis of the chemical properties and solubility curves of neutral and basic
calcium salts of orthoarsenic acid. .
The first type includes:
ACaO?Aa 0?5H 0 - high "solubility" in the pH range 7.5-10: water suspension bey
pH 9.6; nent aiizaiion by acid indicated by phenophthelein takes place after
titrating back approximately 14% CaO;
3C&6?As20--10 0 - high. "solubility" in the pH range 7.5-10; water suspension
has pH 9.1; neftralization of acid takes,place after titrating back approximately
-6% CaO.
The second type inclu&es:
4CaO1"_0.'2H?0 and solid solutions of calcium hydroxide in it with a 0e0 : Aa?0"
ratio equal to'3.e`=3.3; _ov solubility in the pH range water suspension ;ias`
pH 8.3-8.6; neutralization taken place after t!+:,.-ating back approximately 1-2% C&O.
On the other hand,-it is known that chemical analysis of samples by they 1.arcentaga
content of CaO and As20-5.and calculation of the moles ratio ~a0 : As20 in a sub-
stance are no. sufficient to determine the phase composition of the co~pcu .
X-ray analysis is not always obteinhble ant furthermore :,ye graphs cannot be
obtained for many finely dispersal samples. Therefore, we attempted to use the
characteriattes of the above-listed individual. compounds as a method for determin-
ing the prase composition of Salta and their mixtures.
The solubility curves are shown i.n Figure 2. The results of determining the
phase composition of various eamploe by titr*-tien of their saueponsione end "eolniullity"
curves are ahown in Table 3.
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4CaO?-As2O5.5H O, 3Ca0?Aa20?1OH`,O, 3Ca0?Aa205.2H2O and solid solutions were
taken as standard3 for comparis;n.
From Table 3 it is seen that it is not always necessary to record solubility
solution. Actually, if the percent of CEO 1e less than 2 according to the results
of titration with phenolphthalein, then it is possible to say that the compound
belongs to the second type -- i.e. is 3Ca0?As0OG?2H20 or a solid solution, for
example, samples 51 and 57.
By the same token, if titration of the suspension yields a percent of COG
close to 15, then without the solubility curves it is possible to conclude that
the sample is 4Ca0?As?0 5'5H20, for example, samples 58 and 71.
We introduce several examples in which the CaO percent rangos.from 2 to 15
Sample 75 -- CEO - 3.92 percent, Ca0:Aa20 ratio 3.02 according to chemical
analysis. "Solub~ldty" average for pH values 7.5-10; this means that this sample
is a mechanical mixture of 3CeO'AS205?10U20 and. 3Cafl Ae205`2H2O.
Sample 59 -- CEO - 7.84 percent, 0a0:As 05q ratio 3.93. "Solubility" average.
Consequently, the sample is a mixture of 4Ce Aa205.5H2O with a solid solution.
Sample 52 -- CEO - 9.42 percent, CaO:As,OS5 ratio 3.8. "'Solubility" average.
Obviously, thin is a mixture of 4Cao?As205.5l0 and a solid solution.
Sample 83 -- CaO - 4.48 percent, Cc0:As205 ratio 3.35. "Solubility" average.
M. O^=' io 1o a -W o- - .v~'.u.x ov,- .. 1Jauo ?,
r ~~ err ~,i 7::
30 percent solid solution.
If this subL'ance had been a mixture of approximately 30 percent 4Ca0?Ae205.5H20
and 70 percent 3Ca0?As205'2H20, then its solubility would have been lower.
In our physicoobemical investigation we often utilized this r '' l to deter-
mine the phase composition of intermediate and sometimes terminal phases. In a
majority of cases, this method. was of invaluable aaaietence in our work.
r It is obvious that there must not be from calcium oxide in these substances.
If there Is, it !e neceaaary to determine the content of free calcium oxide by
the banzoin method (in an alcohol solution) and allow fir it in the result obtained
by the titration o? the saint?on with a 0.02 N HC1 solution in the presence of
phonophthalein. In this case, a "solubility" curve should be recorded.
1. Two types of compounds were established after studying the properties
of basin and neutral calcium salts of orthoarsenic ac5-i.
Type I. -- 4CaC?Aa205.5H20, and 3Ca0?As205?10H0. Water suspensions
have pH values of 9.6 aMA 9.1, respectively; neutralization of suspensions by acid
dhddoated by phenolhthaleiu takes place for those compounds Whose basicity reduces
to a Ca:Aa205 ratio equal approximately to 2.7 - 2.5 in the solid phase. Both
compounds are highly soluble in the pH range 7.5 - 10; cor:sequently, they are
highly toxic.
Type II. -- 3CaO As2055'2H20 and solid solutions. Water sump-anions
have pH values of 8.3 - 8.6 anS are highly titrated by acid in the presence of
phenolphthal.ain. "Solubility" is relatively low.
It is possible that the marked difference in the properties of these two
types of compounds is due to the different structure of the crystal lattice.
N
I
~~;.vr iyL;~e
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2. An attempt vas made to utilize the results obtainsA. from the 'solubility"
carrel and titration of suspensions of the Individual co*pounde as a Method for
determining the phase composition of unknown samples ami mixtmrua.
3. The data obtained Makes it poesiole to obtain basic calcium salts of
orthoarsenic acids which, due to their sol'ibility in the alkaline range, are
mach nor* toxic than industrial samples now usod.
CO 'TIfEjTLLE
rnnnrmmuTraT.
LAppenied figures follow]
0
-7-
CONFTh ITIAL
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Figure 1.. "Solubility" Curves for the Samples:
L LA an co ao Gn Cn oA 1m
01' af/[i2oif
?7 e 9
N
Figure 2. "Solubility" Curves for the Samples:
51, 52, 58, 59, 62, 71, 75, 76, 78,.83
m
Ga r1l' E1 TI 1
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