INDUSTRIAL AND ENGINEERING CHEMISTRY
September 1947
TABLE111. ANALYSISFOR
.\LT?MIK.4
ON i T S R I O U S
FLOCS
Alkali l-sed t o Prepare Alumina a t p H 4.5
Alkali/Liter H 6 O a Required Milliequivahlilliequivalent (Milliequivalent t o Dissolve lent Required Alumina. hlilliby EquaSiae Required by Equation l a ) equiralentiLiter tion 2 a Present 30.0C 19.7 Yes YaSC03 29,N K O SaHCOs 9.5d 9.7d 6.3 SaOH 6.S 6.9d 4.5 Y O SaOH 3.2b 3.1d 2.1 I’es 4.6 Yes XaOH 6.9b 6.9d NaOH 12.lb 12.3* 8.0 Yes a Equations: (1) 2AI(OH)a ~ H ~ S O ~ + . ~ I Z ( S O6Hz0: ~ ) J (2) 2.41(0€1) 2HsSO4 + 2.41(OH)SO4 4Hs0. b By t i t r a t i o n of alkali with standard acid. C I i y titration of suspension with 0.03 S H2S04, original method. d R y titration of solution or suspension Kith 0.05 5 IISS04, revi.ed method.
+
+
+
+
ni:tterial does not rule out the possible presence of basic salts amorphous to x-ray examination, in n-hich Al(OH), is present as a unit in a larger structure. For exaniple, Kohlschutter (9) propose5 a basic salt of the composition -ilC13.2Aii(0H)3. - k i d ir-ould attack such a structure with the removal of the alumina, and the presence of the normal salt \r-ould have no effect o n the titration. However, the analytical determination of Al(OH), as a chemical unit is attained whether thc initial material is in the complex or the simple form.) TT7hen such a floc has reacted n-ith sulfuric acid and therefore obtained a p H of 3.5, the product in solution is the normal aluminum sulfate. On this basis the revised method of determining aluniina in dilute suspensions and in the presence of size precipitate gives the absolute amount of alumina in the sample. I t may he used on fresh (aged not more than 2 n-relis) n e t prccipitates ( p H 4.5), and consists of adding a known amount of 0.05 sulfuric actd (in excess of amount required by the aluniina present) t o the sample, allowing 16 hours for complete reaction, and back titrating t o pH 3.5 with 0.05 S sodium hydroxide standardized against the standard sulfuric acid. T h e presence of materials other than size and alumina does not interfere unless such materials form a complex with alumina or show buffering action between thc pH values 4.5 and 3.5. K i t h thr
1147
proper volume sample and the use of proper controls the amount of .41(OH)3 may be determined as equivalent to the acid usedt,hat is, formation of normal salt-to xithin 5% or better of the amount of size precipitate used in this investigation. ACKNOWLEDGMENT
e
The m i t e r Tishes t o thank J. D. H. Donnay for the x-ray determinations, and the other members of the Hercules Experiment Station who contributed t o this n-ork. LITERATURE CITED
(1) .lm. Soc. for Testing XIaterials and Am. SOC.for X-Ility and Diffraction, Card Index of X-Ray Diffraction Data, original set and 1st supplement. ( 2 ) Bialkomsky. H. IT.,P a p e r T r a d e J . , 97, S o . 13, 29-46 (1933). (3) Booth, L. M., Ibid.,106, KO.8, 122-4 (1938). (4) Collins, T. T., J r . , Davis, H. L., and Rowland, B. IT., Ibid.,
113, NO. 13. 94-9 (1941). ( 5 ) Datta, K . P., J . I n d i a n Chem. Soc., 19, No. 5 , 191-203 (1942). ( 8 ) Davis, H. L., and Farnham, E. C., J. F‘hys. Chcm., 36, 1057-
74 (1932). ( 7 ) Graham. 11. P.. dissertation. Coluinbia Lniv., 1942. ( 8 ) Inihoff, C. E., and Burkhaidt, L. A , , XSD. C ~ GC. H L V ,35,
873-82 (1943). (9) Kohlschutter H. W., Kolloid-Z , 96, 237-$4 (1941). (10) Mellor, J. ‘X , “Treatise on Inorganic Chemistry," I o 1 V, Sen- York, Longmans. Green 8: Co., I IC., 1942. (11) \filler, L. B., P a p & T r a d e J . , 108, No. 2, 34-40 (1939). (12) Price. D., and Cameron, D. D., P u l p P a p e r M a g . Can., 40, No. 3, 142-8 (1046). (13) ILzd., 40, No. 3 , 143-8, Figuie 2 (1946). (14) Price, D., snd Cameion. D. D., unpublished work. (15) Redd, J. C., P a p e r T r a d e J . , 119, KO.7, 42-7 (1944). (le) Robinson, J. J., Ibid.,103, No. 7, 104-12 (1936). (17) Strafford, N., and Wyatt, P. F., dnalyst 68, 319-24 (1943). (18) Thomas, A. TI-.,and Whitehead, T. H., J . Phys. Chem., 35, 2747 11931). (19) Weisei, H. B., hfilligan, W.o., and Pureell, W. R., IUD. ENQ CHEM.,33, 669-72 (1941). (20) Wilson, W.S.,U. S. Patent 2,323,409 ( J d > G, 19*3). pREsEYTED before t h e Division of C e l ~ u ~ o chemistry se at the 110th lreeting the . \ X ~ E R I C A KC H E \ ~ I C A T . S O C I E T Y , Chicago. 111.
Molal Refractions of Mononuclear Aromatic Hydrocarbons KANCE- CORBIS, ALARY =ILEXODER, -4sn Gb ST-41TEGLOFF l‘nirersal Oil ProdiLcts C o m p a n y , Chicago, I l l . T h e molal refractions of nioiionuclear aromatic hy drovarbons are additi\e in a homologous series, and may be eypressed by a n equation of t h e form R = k + a n , where K is molal refraction, calculated b y either the LoreiuLorentz formula or t h e Gladstone-Dale formula, and ri is the number of carbon atoms. Constants a arid k habe been eialuated by t h e method of least squares for fourteen homologous berieq of mononuclear aromatic h ? tlrocarbons.
R E C E S T collation arid critical evaluation of data on physical constants (3) has made readily available all recordcd values for density and refractire indes of mononuclear aromatic hydrocarbons. These d a t a have been used to evaluate the effect of structure on molal refraction, which is both an additive and a constitutional property. I t cannot be predicted, therefore, unless the effects of structure are known. Molal refraction depends on refractive index, density, and molecular weight. For com-
paratiw studies molal refraction is preferred to refractivc index liecause of the minimization of effects of temperature and density. Molal refractions of aliphatic hydrocarbons for the sodium D line are additive within a single homologous series. For many serici of aliphatic hydrocarbons the effect of adding a CII, group is constant ( I S ) . The effects of structxre, such as incrc,nirnis in nioial rcfraction caused by branching and by unsaturatioii, have been thoroughly investigated and evaluated for alip1i:it ic hydrocarbons ( 7 , 8.13). Physical constant data for aromatic: compounds ai’e uot nt>arly so complete as those for the aliphatics. Th1:y are, 1ion.evc.r. sufFicient to permit evaluation of the relation bet ween molal rt~i’raction and the number of carbon atoms for fourteen homologuu mononuclear aromatic hydrocaarbons. CALCU LATIOS S
Molal refractions have different numercial values, depending on how they are defined. The different systems are internally
Vol. 39, No. 9
INDUSTRlAL AND ENGINEERING CHEMISTRY
1148
cori.&tcnt, but valucs hascd on different i1efiiiitioii.q cwitiot bo compared n-itli oiie aiiothvr. A number of difft~ri~nt tleiiiiitioria have been propoxd. The 1,orenz-Lort~ntL equ:it ioii \\-as developed from the c,li'c,ttoiiiagiieti~theory nt' light :ititl. tliurc.forc,, (11, 1 2 ) . 1Iu.t 01 the ut1ior I'llrlllula* arc' purely empirical, but their relativc of c ; i I i u l : i t i o i i li:is lcd til their continued uae. Tn-o of the inore n.idcly i~iiiplo>.c,dt,iiipii,ic:il relations arc' the Gladstone-Dale (6) and the E?-lini:iii ( j ) I'ciriiiiilae. 1Iolal refractions for the sodium 11 h i e , c:ilcul:itcd liy tliwi' equations, n-erc used iii thc present stutly: Loreilz-I,orciit z formula,
Gladstone-Dale formula,
Eykman formula,
(3) vihr'rc I~I., Xc, and RE = iiiolal refrart ioii, 31 = ~iiol(~rul:ir weight, d = density, 1- = molecular roluiiic~,aiitl t i l , = rc~i'rai~tivi~ index. I t has been stated t h a t iiiolal refrnctioii is virtuully utial'i'ectc,tl by temperature ( 1 , 6 ) . Hon, later studics >Iiii\v that tlitx effect of temperature on molal refractioii ia aclwilly sigiiificxrit for R L a i d XG. ' R,c increases viith inci,c.:isiiig triiipc~rati i t ' c , . wheieas RG decreases with increa,iriy t i ~ i i i ~ ~ ( ~ r ~ ~ tTlic) L i t , i i.:yIitidex. Iiurtz and IT-arcl ( 1 0 ) c h o \ \ i > t l tli:tt t l i i relation ii nearly constant for a large number of coinl,ouiitIs, alii1 Anu = 0.00 A(!
(4
Wieri Equation 4 holds, REis affected r c r y littlc bj- tciiipc~raturc~. r, n-hen the temperature coefic.ic>tit. of I i o t l i clcii-iL>- aritl refractive irides arc evaluated froin c~xpi'riiiii~iitd (lata, their ratio frequently deviates from the tlieoretiral v:ilue of 0.60, and RL. i q not coiijtant ovi'r a range of tempc~ratulr. The tlata 011 aromatic, compound4 are iiisufficierit t o detcrinirie \\-lietlier all the vui:itioti* are cauucd by inaccurate experiment:il values, or wlicthcr the, value of 0.60 should be modified for some t>-pcs of cciiiipounti~. Since the rate of change of molal refraction (Xi,/ < G
