Catalytic Effect of Ruthenium Compound on the Reduction of Perchloric Acid by Hydrobromic Acid Citation Carter, James Maurice (1926) Catalytic Effect of Ruthenium Compound on the Reduction of Perchloric Acid by Hydrobromic Acid. Bachelor's thesis, California Institute of Technology. doi:10.7907/3QJZ-MK77. https://resolver.caltech.edu/CaltechETD:etd-12302004-142437 Abstract No abstract. Item Type: Thesis (Bachelor's thesis) Subject Keywords: Chemistry Degree Grantor: California Institute of Technology Division: Chemistry and Chemical Engineering Major Option: Chemistry Thesis Availability: Public (worldwide access) Research Advisor(s): Yost, Don M. Thesis Committee: None, None Defense Date: 1 January 1926 Record Number: CaltechETD:etd-12302004-142437 Persistent URL: https://resolver.caltech.edu/CaltechETD:etd-12302004-142437 DOI: 10.7907/3QJZ-MK77 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 5167 Collection: CaltechTHESIS Deposited By: Imported from ETD-db Deposited On: 30 Dec 2004 Last Modified: 03 Oct 2019 23:41 Thesis Files Preview PDF (Carter_jm_1926.pdf) - Final Version See Usage Policy. 3MB Repository Staff Only: item control page

CATALYTIC BPFRCT OF RUTHENIUM COMPOUNDS OF THE REDUCTION OF PRRCHLORIC ACLD BY TWYTROBROMIC ACID Thesis by James i. Carter in partial fulfillment ef the requirements for the degree of Kachelor ef Selence in Chemistry. CALIFORNIA INSTITUI™M OF THCHNOLCEY Pasadena, California 1926 CATALYTIC EFFECT OF RUTHENIUN COMPOERDS oF TI! REDUCTION OF PYRCHLORIC ACIP BY NYDPOBROMIC ACID. Purrese. The purpose of the present investigation has been to determine the nature of the catalytic effect shown by ruthenium compounds on the reduction of perchlor- Ac acid by hydrobromic acid; and, ££ possible, to deter- mine the mechanism of the reaction. Underlying theory. The reagtion just mentioned is a food nase of homogenious gatalysis, and offers possibi-+ lities of discovering: more sbout:.bo th the oxidising power of perchloric acid and the chemistry of ruthenium. in fat- ly dilute solution, perchieric acid is extraordinarily ‘table, even “hen hots A few métallic ions, (Ti) or’y Mo””*) besides ruthenium ion, are the only eubstances that have a reducing effect. on at in cold dilute solution. It ‘is knom to oxidize ruthenium. compeunds to the tetroxide in hot, fairly concentrated selution; the fact of cata- lysis indicates a possibity of thiw in dilute solution as vell. Investigation therefere seeme of value as of- fering information on the nature of oxidation by per- chloric acid, a8 yell as the relative stabilty of dif- . ferent compounds of ruthenium $g0arde oxidizine and 1) System of qualitative. analysis now in preparation by Dra A. Ay Moves and Dr. W. C. BY aye reducing arents. | | Previous work on the problems | fre R. WH. Dalton (of this laboratory, while working on the complete oys= tem of cuslitative smnalysis nov in preparation by Dr. Ay A, Foyes discovered the catalytic action of ruthen- um salts. At one noint in tha prosedure for the pre« paration of the selution for analysis, hydrobroma¢. acid is removed by adding parchleric ackd and boiling. By. alten noticed that with 2 sample sontaining ruthenium, free bromine was civen off on beiling; and a repetition confirmed this fact. br. Noyes suggested a more ermplete investication of the fact as a research problem hich 1 have undertaken. ‘Diecussion | the reaction between perchioric and hydrobromic acids: HOLO, + @EBr = HCl + 4H, @ + 4Br, (2) must fo to completion in a thermodynamic sense; no res versal is vossible. However , blank experiments shoved ‘that no reaction toek ylace aver with SN perchloric acid ‘and small amounts of hydrobromic acid on boiling the so- lution. On the addition of very email’ quantities of ru- “thenium tri-chloride or tri=bromide, bromine imrediate ly bercan to be vroduced. Since ruthenium shone evary valence from one to sicnt, (the pentavalent oxide has C2) ‘recently peon shown to exist) Et. _appears that it may nere act as a carrier catlyst, beine alternately oxid- ised and reduced. It is evident that much might be learned by an investication of the rate at which reaction (1) procecds, and of the effect of chan-e§ in ceneentration that the » reactine substances and the catalyst have on the rate. Aise, since the ruthenium is presumably oxidized during the course of the reaction, an investisation of toe ac- tion of perchlriec acid on ruthenium salte, and of the effect of bromide ion and free bromine or them, should alse be of great interest. | Experimental Methods For measuring the rates, if is most convenient to determine the breuive produced in a definite time. Preliminary work showed that tne rate was easily measur- able at 100 degrees, using moderately dilute concentra tions. in the method first used, the solution contain ing the reacting substances was placed in a glass-stop-~ pered distilling flask nrevided with a gas inlet tube leading to the bottom of the flask. The bromine produced could then be swent out with «a atrenn of carben dioxide and led into 2 solution of petesaium iodide, ain which the dodine liberatd could bs determined with @ thicsulphate ‘solution. By changing the racesving vosece] containing the icdide a t regular intervale, the rate could be followed, 2) Hs. Remy, Z. anore. chem. 126 EB50eG2 (1923) 4 the reaction falsk was immer sed in a steam bath; the car- bon dioxide before entering wae led through a simlar flask containg hydrobromic ncid at the same concentration as that used in the reaction. This was done to prevent evaporation ‘and less of hydrebromic acid and water. “his arrangement praved. vary unsatisfactory, how ever, as evaporation and less pf hydrobromic acid and wa- ter with the subsequent changes in concentration eould not be avoided. This and. other disadvantages led to the adoption eof ancther method Yor following the rates. A method offering fex disadvantaces found. ihe re- action solution wae made up at room temperature, by meas- “uring definite volumes of the reacting substances inte a volumtric flask by means of precision pipettes. The total ‘volume was then made up ti $80 m1, thoroughly mixed, and mall portion removed inte test tubes, which vere then segled off and olaced in a water beth af 100 degrees. Tubes were removed after varying lengths ef time, cooled to room temperature and breken under icdide selution. The lodine was then titrated aguinet thiosulptate. The size of the somples cculd be adjusted to suit the time of reaction, 20 ml being convenient for samples heated for less than half an hour, and 5m] fer samples heated for lenger per- iods. | An exactiy similar method wae used for followings the rection between perchleric acid and ruthenium chloride. Preparation of Selutions Ruthenium. Ruthenium tri-bromide vas prepared by eonverting «a weighed quantity of the triechloride inte “hydroxide and digeselving in hydrobromic acid. The solution Was made wp to be 8.710 N in acid andto certain 2.50 mem . of ruthenium perml. Later ruthenium triechleride solution was made up by dissolving a weighed quantity of the anhydrous selid in 50,00 mi of water and adding 6.00 ml of 6! hydrechlor- de acid. “his solution contained 8.88 mem ef ruthenium per ml , and was slightly over 0.5% in acid. The acid was found necessary to prevent hydrolysis. A selution made up by vr. Talton was aleo used for several experiments. it contained 10.00 mgm of ruthenium per ml, but the seid contert was. unkrom. It was probab- ly nearly the same as in my ‘solution. Perchleric Acid. The 602 €.P. acid was diluted te -gbout 3F and titrated acairest sedium hydgoxide solution. It cave no test fer free chlorine nor chloride ion. Hydrebromic Acids ‘the C.P. acid of ep. gr. 1.49 vas upéd. lt was also titrated saeainst hydroxide selutior. The coler wae slmost water white; only very inaporciable amounts of bromine. | . Potassium tribromide. A solution made up by ir. Yost was analyzed fer bromide ion vith silver nitrate, and for free bromine with thiosulphate, after the addi- tion of potassiun iodide. ledine and Thiosulphate, ienth normal selution were made up and compared with each ether. The iodins was “then stardurdized against arsenious oxide. Other chemicals used. che othr ehemicals used were potassium iodide, bromine and carBon tetrachloride. C.P. materials were used throuchout. experimental Tata on the Rate Axperiments. Results of the rate experiments are given below. ‘The results for one experiment usines the flask method are piven, not so much for the ~nformation of the rate, but ag an example of 2 reaction the has gone to completion. in the first eclumr is river the tohal time elapsed, and in the second, the volume of thiogulnteate solution re quired for the titration wf the iodine liberated by the bromine formed during the interval preceding. Series A. “Eperiment 2. Volume 72.56 ml Ru as huCl, 28.0 mem 0.428 milli-mel Ebr 7.90 0 ucla, 9.251 ¥ . iSimin 33.60m1 25Smin 4.44ml 15 min &.80 wl LEG 8.57 270 £443 30 13.29 , 38 18.81 285 6.50 a5 24,65 180 - 8496 30 2.56 69 15.73 , Iss 10.17 Si6 1.56 75 16.18 . 30 16.56 2.0 8.20 333 Lead 105 17.90 225 55.3 120 16.35 240 4.16 fxperiment 2 continues Yotal thiosulphate used 211.43 ml Br evelved 24,2 milli- equivalents. . Oxddizing equivalents of HC1O,/in solkation 26.2 Wquivalerts Br per mole of Ru Ss, | This experiment shows the enermoeus catalytie effect of the ruthenium, and also the fact that the reaction will preceed to completion if the ‘romine is removed as it is formed. ‘he other experiments of this series are not worth much in a quantitative way, ag the errors from evan- ‘eration losses and chanres in concentration are very larce. ‘he only conclusion that could be drawn vas that the rate varied vrobably as the concentrations ef Ru and C10 in table I are given the resuite of the rate ex, - periments by the second wethod as well ae several blank experiments. in the first. column the time of “eating in the vater bath is given, in the secend tha bromine evel~ ved for a 100 ml sample, in milli-equivalents. | Table I | “txperimental Data ef the Resection Rate Experiments. HClO, o«I562 N HBr 0.986 NW Ruir, 0.00128 F 15 min 0,268 millieeq. “60 nin 0294 milliveg. 30 9.505 a is) 1.03 45 0,825 a0 1.14 Table 1. Exp. & Hxp«S .. HClO, 0.2905 N, HBr 0,871 N, HCLO, 0.7362 N, HBr 0.871 N “RuBr, 0.00123 i Rubr, 0.00123 15 min 0.508milli-eq I5 min 1.25 milli-eq 30 Y.10 30 2.28 45 1.32 45 3.12 60 1.56 60 3.96 75 1.79 15 4.86 90 2.04 90 5.32 120 2.46 120 6.24 150 2.84 150 1.33 24 hnre 5468 24 hr. 15.19 Exp. 4 . Exp. 5 HClO, 0.2905 KF, HBr 0.871 8, HVLO, 0.2905 ¥, HBr 0.871 N Rubr, 9.00246 x RuBr, 0.00246 #, KI 0.06 1 16 0.929 i5 0.908 30. 1.53 30 1.65 45 2.08 45 2,29 60 2.38 60 2.75 75 2.62 75 3.12 90 2.94 90 3.82 120 3a3% 120 3.76 150 3465 450 4a17 Table J Expe 6 Same as for “ixn. 5 Except If min 30 45 60 75 90 120 © 150 FI 0.00120 8 02874 milii-eq 1.74 2,61 3.16 3.58 4.03 An 56. 4,88 Exp. & HClO, 1.385 N, HBr 0,940 ¥, RuCl, 0.00246 NM, KI 0.0301 1 15 30 65 60 75 20a] 27al 3068 4548 S006 fame as for 7. “pe 5 except FI 6.0301 i5 min 390 45 60 75 90 EXD « 9 0,958 milliecg 1.88 2074 3262 4,51 5.38 6270 7.25 MELO, 1.395 NW, Wer 0.940 5, Rwod 0.000874 , KI 0.0301] WN 18 BC 48 60 90 120 10.5 15,80 19.6 2ae4 2648 3204 Z Letts Pf Pb FE oF? vd Of peat a bint {ALSIDOS shuwygio.op sawed i i i i i jt ane ch i : See i rj t t hey | bie 1 i 1 i i i ‘ ma ~ wammae nee aa A C. i an ! pe 7 { " i a i fa | : Sat | cachet f ! t : i r. L na me nna i iL 3. a a : 1. ; f i t+ 4 = = : x > > i 7 i zi 4 1X) ; = y 8 = a Be Le e , at ¥ bs [3 4 Lo 2 oT Lug | E E eee Been a FI ' A y 4 N aN y in} y : aa y . 7 co 4 A ~ S i a L i ct i : : 7 j t fea oa : t { ie { | ON t i . de Ae axes we EE a j y 4 7 A 4 | r “Weed cP - 3 ha cH | a mt men wl ae it t 1 i L Ly 1. mt mt 1mnF +. fH rT ee, t Lt iw ans 4 ju i ae mt us is 9 Tt Li. 1 1 Li CLE a ~ 1 xa " imme wes mi t do i * tbe EY O07 CLS ~ be 27 C7 eC'e by! oF anal Tere fable I Exp. 10 Expe 11. Remainder of scelutior from HL, 0.2905 ¥ “xp. 8. Run at 25 degrees HBr O.871 F 95.56 Ars 2243 milli-eqg 3.5 WY s 0,09 milli-eq. interpretation of the Hate Experimerts. ihe effect of the concentration ef perchlorate ion is easily determined. In Sxmeriments 1, 2, and 3 the ratio of perchlorate ion is very nearly 1:2:5. A comparison of the relative amounts of bromine formed in the sane time shews thatthey alse are very rearly in the same ratios Hydrocen ion does not vary greatly in these experiments. The effect of the concentration of the ruthenium ig also easily determined. A comparison of the rate curves for Experiments < and 4, shows thet the rate varies lin- early with the concentration of ruthenium. ‘his fact can also be deduced from experiments in whieh the perchloric acid concentration varieca by reducing the resulte to the ®ame concentration in accordanse with the way the rate Varies with the perchloris ecncente ation. Tne resiits are quite consistent throuchout. The effect of removal of bre«ine from the selution is shown by the grarhs of oxperiments 4,5,6, and 7. in these experimentea, small amounts of yetassium iodide vere introduced. 1% is se-n thet the rate continues st ite iI initial value until all the iodide has been oxidized, buth that as secon as bromine started te accumulate, the rate de« creases as in the other experimenta. chie indicates pose sibly an equilibrium between the ruthenium and bromine to form some inactive ruthenium compound. 1t was planred to increase the amount of iodbde in the solution, but the : precipitation of ruthenium triwiodide made thie impracti- cal she iodide does not effect the reduction of ruthen- ium below the trivalent state, however, so that any abjec- tion on this ground is met. the effect of the concentration of hydrogen ion is not yet determined, althouch it is evident that it has sos gome effect. A comparison of the rates in expariments 4 and £ shows that ~hile the cencentration of perchlorate ion has been changed by a factor of about five, and that of the hydregen ion by a facter of about two, the rate has increased by about twerty times, (twerty six, if the extrapolated initial rate is taken in “xperiemtnt B}e it seems that the rate is dependent to 3 large depres unen the concentration of hydrogen icne temperature Coefficient of the Reaction. From the data of “xperiment 10 cempaered with Sx _ ‘periment 8, the temperature seetficiont can be calcuala- ted, and ia found tebe equal to 2.21 for a ten cecree rise in temperature. 3) Gutbier and Trenckner, 2. anorge chem. 45, 166, (1505) iz Reaction of Ruthenium Chloride and Perechloric Avid An investigation of the section of ruthenium tri-— chloride snd perchloric acid was undertaken, to determinne if possible te what state ruthenium is oxidized during the reaction, and in the hope of finding an intermediate com« pound. First it was attempted to prepare ruthenium tri+ _chior&de, but because of the hydrolysis of ruthenium palts at low hydrocen ion concentration or high tempera~« turse, (above 50 degrees) it was found impractical. the formation of an oxychloride on hydrelysis mares the re= ‘moval of all the chloride almest impessibie. Later, it was thousht that it micht be poscible to follow the course ef the reeaction between the ruthenium and the perchloric acid by determining the increase in ehieride ien on heating a mixture of the two. “owever, silver nitrate even unfer the best cenditions could never remove all of the chleride, even in quite acid so- lution. Finally, #t was found vossible to use the same me- thed as in the rate experiments. 4s mentioned before ice- @ide fon deed not reduce ruthenium below the trievalent state, so ihat the ruthenium ie at the end in the same stare ae in the becinnine. A time correction had to be made from the time that the iodide was added, however, as of is course as soon as it was added, the reaction (1) , civen ‘on pace 2 began te occur. . in the first column of the table are given the times .of reaction at 100 degress,; in the second the axididaticn equivalents as determined by titration ef the iodine liber ated; and in the third the ratio of the eqivalente of 10- . dine liberatd to the moles of ruthenium oresent. ixperimnent 12 10.00 ml samples containgng Pach, and neo Ruch, 6.427 milli-~mois HClO, 15.92 milli-mols 8 .¢) 0.342 0,800 2i 8 02430 i005 Tubes that were heating for 2 longer time broke in ‘the water bath andhence no irfermation could be obtained as to whether the oxidation preceeded past the valve fount. Aes time vas limited it was decided to run another experi- ment, but th heat the mixture to a higher temperature, and speed up the reaetion. This method ia open te ebjection, as it is suite possible that other reaction will tare place at a hicher temperature, but any information that can be ebtained is of use. A tube of solution the same as that used in the other experiemtnts was heated for six days in xylene vapor | — iDep. 140 degrees). At the end of that time, there was a4 14 .ghear, brom™m liquid and a black precipitae in the tube. 1t was desired to beep the liquid an‘ the precipitate separ- ate, ge that the tube was rot epened under dodide solution, but the end wae cut off. “here was considerable <as pressure “jn the tube, and the odor of chlorine was quite strong on. opening. On this account, the titrataon does not represent an accurate value of the oxidation of the ruthenium, but is teo low by an urknewn ameunt. After opening the tube, the liquid was remeved with a pinette, and poured inte potassium iodide solution. the pracipitate was washed and the washings added to the liquid. | The solid was then divided into t-o parts; to one of them potassium bromide in vater was added. Fo bromine was formdd. To the other potassium iodide was added, and iodine was ime mediately formed. that this was due to reduction cf the eolid and net to emall cuantities of the liquid reamairing was proved by the fact that the last wash water barely colored potassium solution. Potassium iodide wae finally added to the first part of the solid, and the total ice dine liberated by the solid titrated against thiesulvhate. A solid residve of black metallic scales remained after the treatment with iodide, and did not disselve after seve eral days. halli- mols of BuClyin solution 0.874 _ squivalente of i,from liquid 0.876 « ® « from solid 0127 Total eqivalents of 1 per rol Ru ie0id is These experiments ould seem to indicate that per- ehloric acid oxidizes the ruthenium to some state higher ‘than the pentavalent. Further work on this should be of intereat. Reaction of Huthenium Chleride and Bromine. From the effect of the accumulation of bromine on the rate found in the rate experiments, it might be sup- - pesed that an equilibrium existed between trivalent ru- thenium @en and bromine, to give some more highly oxidized gtate and bromide ion. In order to measure the sunvesed equilibrium a series of experiments were undertaken. - In carrying out the exverimerts, soluticans contain- ing know amounts of ruthenium trichloride, potassium bre- mide, and bromire were placed in stopoered bettlies in con<« tact with a measured volume of carbon tetrachloride. at te samé time planks containing no ruthenium were treated in b the sane way. The bottles were potated in the thermostat at 25 degrees for several days, then portions of the car- bon tetrachloride were removed «ith a nipette, and sfter “addition of potassium iodide were titrated aceinst thio- sulphate. Frem the difference in the concentrations of bro- mine in the sample containing the ruthenium and the blank, it should be pessible to calculate the amount of bromine reacting with the ruthenium. Prom several sets of excere iments, with different amounts of ruthenium and bromine, it should then be vossible to vrove the existance of an 16 equilibrium if one exists and to measure its constant. The results yielded no quantitative measurements, partly because of leakage from the bottles, which was al« ‘mont impossible te avoid; and also because of the fact éaiecovered later that there was no equilibrium, but that | ruthenium trichloride and bromine neact irreversibly. it wae noticed that the bromine in the carbon tet- rachioride phase ef one of the samples that had stood for several days had disappeared. io decide whether this was due to leakace of to an irreversible reaction more bromine was added and the mixture let stand for sever al days. At the end of this time the eample was repeatedly shaken with carbon tetrachloride until no test for bromine was obtaind. ‘the solution retaired the wine color it had assumed in the addition of the bromine, and shoved no signs of giving up bromine after standing in ceortact with carben tetrachlo- ride for tye days. experiments on the Brominated Ruthenium Compound. Since the vrecedirg experiment indicated a complete oxidation of ruthenium by bromine, which appeared to be dyrevorsible, it was decided te test portions of the selu- tien containing this oxidized compound with 9 viey of de+ termining its state of oxidaticn and its properties. che solution was know te contain 0.0437 milliemols of ruthe -endum per mi, or slightly less because of losses in shaking i? with carben tetrachloride in removing fres bromine. Be A 10.00 ml sample vas treated vith an excee of potassium iodide. The color changed rapidly from the charac “teriste wine shatie of the axidized compound te the yelias ‘provm color corresponding to the tri-valent ion. The ic- dine liberated was shaken cut with carbon tetrachloride, and titrated against thiosulphate solution. Because of the large excess of iodide ion , the iodine was removed with difficulty, and probably net 211 of it was removed. Ap excess of bromire was then added to the reduced solution to reoxidize it. The removal of the excess of fres brominewas attempted after the mixture Has stood for four days, but the harce corcentration of bromide slready | referradte, reduced the distribution ratic between the solution and carbo tetrachloride te such an extent that the remeval was very difficult. for this reason wher iodide was again added, a large excess of iodine was formed by oxidation with the unremoved bromine. énothsr sample, of 20.00 mi that had been in con tact with bremine for five days vee reduced with rotacsium dedide in the same manner as the first sample, sxcept that care vas taken te add only a very elicht excess. After all the iodine formed had bacn removed a small additi mal amount of iodide was added, but no further iodine vas formed. is Experiment is in the first column are given the milli-equivalents of i, “fepmed; in the second the ratio of the i,formed to the Ru present. 0.357 0.82 onan Yt aff * 0.683 0.78 | The actual ratios of the equivalents of iodine formed to the mols of ruthenium present should vorebably be slightly hicher, ae some of the ruthenium was unavoidably lest in repeated shaking with carbon tetrachloride. It appears that tri«valert ruthenium is oxidized to the tretra-valent state by bromine, and that this cem- ‘pound is quite stable as it desea not give off bromine at room temperature, bs. A small velime of this sme solution used in the previous experiment wac ditilled, and the distillate col- lected in potascium solution. "oe trace of color appeared in this solution, shoving that the oxidized compound is : stable even at 100 degrecs. | Ge Reducing acents suck hydrazine sulphate and po- tassium isdide, (already noted) reduce the ruthenium app afentiy giving the original tri-vralent form. ds. Alkalies precipitate all of the ruthenium te eive a black or vary dark solid. ig GY) Ho Hewe mentions the oxidation of the sodium or cther alkali aquo-brom-ruthenates to form the chlor-ruthenates by means of bromine. The cresent case may be something sh milar, although there is nothing in the l&terature con- eerning the oxidatien of tri-valent ruthenium chloride alone, Apparently the alkali ruthenites and ruthenates, or rather the bromeruthenits and ruthenates, are much less ‘gubject te hydrelysis than the simple salts, so that most of the work concerning the ruthenium halides hase been done on these compounds rather then on these which were -used in the present case. Catalytic ffect of the Oxidized Ruthenium A vats experimert was run as in the series made previously, excent that the exidized ruthenium solution vas used, The solution was made up te 100 ml, and samples sealed into test tubes and heated for different times Uxperiment 14 “HC1Q, 042785 N MBr 0.9404 ¥ Ruthenium 0.00218 (approx) iS min 0.0795 milli-eq. 30 0.159 60 CG. 487 90 0.748 150 1422 122 nr. 25 mir 16.30 To one sample was added a small amount of potas« sium iodie, about a 507. amcess over that required to re@ dace the ruthenium to the trievalent form; it wae then -ge@enled in a tube and heated for 15 minutes in the water bath. | iS min 2664 mil li-eq. ‘this represents an inereasa in the rate by a factor of 20. . These two experiments show that the oxidized form ef ruthenium has no catlytic action. ‘the slow rate found in the first experiment can be axplairned by the presence ef only four per cent of the total ruthenium in an unoxe idizec, state. this is quite probable, as the reaction be- tween the tri-valent ruthenium and bromine is slew. Niscallaneous (ualitative Experiments. Ae Sxperiments on the dark solid residue remain- ing in the flask at the end of rate experiments conduc- ted by the first methéd. Small amounts, a8 nearly sequal as possible were treate¢ with various reagents. ds KC10, added oor nO Betion Be * ® solution heated«-- no action 3 ' end UCL added; gelution heated -«no action 40 HO, added «== ne action 5s et solid let stand in the air«- wine color de- ¥Yaloped in the selutbon on addition of water 6S. Solutien ef Rubr treated sith ECIO, «= assumed wine color, same as 5 ?. Sodium sulphite, hydroxylamine, hydrazine sulpa ate, a1] caused reduction vith appearance of Qualitative Experiments AaTe the yellow brown t#i-valent rutheunium ion Be Experiments on the solid residue remaining in the reaction of RuCl and HC1C, at 140 degrees. le KBr added«=- no action 2. K added == 1,1iberatédd imm ediately. Not all ef the precipitate dissolved; emall me- tallie sesales remaineds Conclusions. YXot enough facts are know to formulatea mechaniom for the reaction (I) on page 2 with any degree of surety. ‘From the facts knowm, hovever, a tentative mechanism may ‘be suggested. Rurther work will serve to either prove or ‘overthrow the theery suggested. from the experiments on ruthenium and perchloric -aeid, it is shown that puthenium is oxidized te some ‘walance higher than thre-, possibly five. Bremine is show te oxidize tri-valent ruthenium to a higher valence which seems te be four. (See note on work of Howe). | The fellexing mechanism is then suggested: Ru’ "+ clOp = Ru + ClO> (a) ter fork Bul Cle; - Ru + ClO} or ClO or CL, (2) Ru Br | Ru + Br, (3) Res Br, = Ru + Bra (4) | Argument. Reaction (1). This fellive from the ex= periments on ruthenium tri-chloride and perchloric acid. Reaction (2). Perchleric seid ke know to oxidize ruthenium salts to the tetroxide in het fairly concen- trated solution. (Ses note on Palton's work). It seems quite likely that this ray take place slowly in more dilute solution, and that the oxidation «ill not stop at the ren- ‘tavalent form shown in (1), but will co further. Reaction (3). The six, sevem, and eight valent states of ruthenium do not appearte be stable in acid eolution® i but decompose in the presence of hydrochioric or nydro« bromic acids to give chicrine or bromine. Since in the first reaction rate data given, it is seen that the reac- tion gees to completion when the bromine is removed, it is evident that the tetravalient ferm is net formend in the de= compsition, ap this has beson sho to have no catalytic action. Cf course the end product in reaction (39 might be the trievalent forms . Reaction (4). ‘This fellows from the experiments on the actien of bromine on tri-valent ruthenium. 5S). 'axtbeok of iInere. Chem. (J.N.Priend, %d.} Vol. IX Part 1 page 147 Gutbier ue Ransohoff, Z.anorg. chem. 45,243 23 Conclusions. Prepesed experinentato determine the mechanism. xX. Continuance of the rate experiments up te a ‘lengrer veriod of time. The mechaniem sugcested vould cive 8 constant cate, as when no tri-valent ruthenium was any longer present, the decrease in the rate due to the ree# moval by bromine would cease. 2 Use of ruthenium pentoxide as a catalyst in place of the trichloride, The rate should in this case not be affected by the accumulation of bromins. | Se The effect of the concentration of hydrogen ion and of bromide ion on the rate should yield interesting results. This vork has been cerried out under the direction of lir. Don Ms Yost. Thanks are due him for many valuable and helpful sugcestions, and also to Dr. Neyss, she sug- gested the investigation. Summarys i» The reaction HClO, + SHBr - HC1~ 4,0 +4Br, has been found te be catalyzed by salts of tri-vaient ru- thenium. ae ‘he rate of the reation has been measured at 100 degrees and at 25 decrees under certain condition, and the teaporature coefficient of the reaction determined. 3, Both Ru ““and Cl07have been found to affect the rate, vithin the limits of error, directly as the first powervof their corcentrations. 7 24 Summary 4» H ion has also beon show to affect the rate. 5. Perchioric acid has been shown te oxidise tri- yalent ruthenium to 2 higher state, possibly the penta« valent. 6. remine has besn shewn to oxicize tri-valent ruthonium irreversibly te the tetreevalent state. 7. The tetraevalent ruthenium has beon shom to fave no catalytic actiom. 8. Potassium iedide has beon shown to recuse tetra- valent ruthenium to the tri-valent. This sows that the reduction potential lies between that of bromine ané ice ‘dine. % <A tentative mechanism hae bes sugested for the eatalytic effect of ruthenium on the reaction under ine vestication, and experiments outlined which should settle the matter, 4}. (Sheuld have ben included on page is) Howes, Je Ame Che sm. Soc. 26, 543, (1904)