Heat of oxidation of aqueous sulfur dioxide with gaseous chlorine

Abstract

The heat of oxid ation of aqueous s ulfur diox ide ,,·it h gaseolls c hlorin e has be(, 11 deLermil1 ed by calorimetric m ethods. Thc results cOl"t"cspond to thc reaction:Cl,(g)+ SO ,·2500 H 20 + 2502 H ,O = I-I 2SO,·25 00 FLO + 2 (H CI1250 H 20 ), 6H(25 dc) = -77.28 ± 0.14 kcal / mole. Thc h eat of form ation of aqlleo us s ulfuric ac id (ill 2500 moles of lI"atcr) has becn calculated t o be -21:3.92 kca l/ moic . . Introduction.. An investigation or t h e heats of solu Lion an d c, oxidlttion or sulfur dioxide to sulfuric acid usi.ng /" bromine as the oxi.dizin g s ubstance wa s recc ntly mad e n,L the U niversity of Lund, S weden [1]. 2 Altho ugh Lhe data on the hetlLs of solution or sulfur \ dioxide were in subs tn,nLi,\l agree ment with tlte prc-( vious datft [2] Lhe cH.lculatecl h ea L or formation of j s uUuric ftcid clifrerecl by ftpproximaLcly 0 .3 kenl/ mol e from t L te resulLs obtain ed in sevcmL r ecell L c!eLcl"-;: mination s [:3. 4, 5, 6J. Becau se the heaL of forlllaLion or s uUuric a,cid sec ms to be well s ubsta ntiaLed it. see med probn,ble that the di scr epan cy mu sL be ntt ribuLed Lo the data on thc h eat or for ma tion of hydrobromic ariel. It see med des irable, ther eforc, Lo , ma,ke a new clctcrminfttion oC Lh e h eaL or oxidaLion , of sulf"ur dioxide using chlorin e as 1 he oxidizi ng agc n t. "( The combin ed data would b e indiC'i1tive or tile consistency between Lhe data on hydro chlori c <1,lld hyclro-( bromi c ac id as well as that bet ween Lite ch1,ta on sulCul' dioxide and sulf"uric acid. An error or 0.15 ]ccc1,1/mole in the h eat of formation of hy drobromic acid could acco ull t ror the apparently high value obtained for I tlte heat or formation of sulfuric acid obtained from ... the h eat or oxidation of sulfur dioxide with bromine. . Thiosulfate SolutionThe 0.05 N sodiulll thiosulfatc soluLion wa s prepH.l"ecl by adding 25 g of re,1,ge n L-grade sod ium Lhiosulfate p en La hy dmte and 0.2 g of sodium carbonate to 2 li ters of water. The concentn1Lioll or . the soluLion WU i'\ determilled by companson with li te 0.1 N ioeLi ne solution . . Sulfur Dioxide Solutioni\. mass-specLrometri c an alysis 01" the grtseous s ull"ur dioxide W,lS perform ed by E. E. Hu ghes or lIlC Applied An aly tical ResC<tl"ch Section oC the AlI<1,lyLical and Jn organic C hemi s try Divis ion . The ,Inalysis gave Lhe followin g results in m ole percen t :98 S0 2, 1. 3 CO, 0.4 N2, Hnd 0.2 082. The 0.15 M s ulf"ur clioxille soluLion was prepared by passin g the gas tlu·ough 4 liters 0[' cI is Lilled WItter from whic h ail" and CO2 hftd b een removed by boilin g. A slight excess or S0 2 was added. This excess W<lS htLer remo ved by passin g a s tream or niLrogen througl) tlte solution while s Lirrin g which nlso removed mos t 01" Lite CO and CS2 impuriLies. The solution WH S protected hom li gh t by coverin g the bottle with aluminum foil. A slig ht press ure of nitrogen was main tain ed over the solution ; r emoval from the bottle was by means oC a siphon . Th e concentration oC tbe solution was determ...

Heat of solution of ammonium bromide and the entropies of the aqueous NH4+ and Br- ions

“…Parker (24) mentions data that lead to AH°values between -8. This value is based, in part, on recent thermochemical data (11,12). This AHf and the entropies of Br2(liq) (16) and Br~( aq) permit a calculation of AG?…”

Formation Enthalpies of C3 and C4 Brominated Hydrocarbons: Bringing Together Classical Thermodynamics, Modern Mass Spectrometry, and High-Level Ab Initio Calculations

“…The enthalpy of reaction 72 was obtained from a thermodynamic cycle involving SO 2 oxidation with Cl 2 (g) and Br 2 (l). , To close the cycle, the corrections up to 14 kJ·mol –1 had to be applied to the measured enthalpies. Using the enthalpies of dilution from the National Bureau of Standards (NBS) Tables, the reaction enthalpy of −94.0 kJ·mol –1 can be obtained instead of the original value of −91.3 kJ·mol –1 .…”