7# 87XXXXXff ""4Px  *6X 6^ Chemistry 142 RATE OF REACTION: THIOSULFATE DECOMPOSITION INTRODUCTION In this laboratory you will study the decomposition of thiosulfate ion in hydrochloric acid solution. In the first part of the experiment you will determine the dependence of the rate of the reaction on thiosulfate concentration and on changes in temperature. In the second part of the experiment you will design your own study. The possible areas for study are: 1) Determine the dependence of the rate law on HCl concentration 2) Determine the effect of various concentrations of sodium sulfite on the rate of decomposition 3) Determine the activation energy for the reaction This reaction has important implications for photographic chemistry. Thiosulfate (S2O3-2) is used as a chelating agent (fixer) to dissolve excess AgBr in processed photographic emulsions. The decomposition of thiosulfate into sulfur must be avoided, so sodium sulfite is added to fixing baths to prevent the decomposition (see study topic 2, above), and the solution is kept alkaline. PART I - Background The rates of chemical reactions are expressed as functions of the concentrations or partial pressures of the reacting species. The rate, R, of the reaction H2(g) + I2(g)  2HI(g) (1) is found to be proportional to the product of the partial pressures of H2 and I2. The rate of this reaction would be written R = k PH2 PI2 (2) where k is the proportionality constant, P denotes the partial pressure of the reactant, and any bracketed quantities are concentrations in moles liter-1 (as in equation 8, below). The proportionality constant is called the rate constant and depends on the system under consideration and the temperature of the reaction. The sum of the exponents of the concentration terms is called the order of the reaction. Thus, reaction (1) is second-order overall. The reaction may also be said to be first-order in hydrogen concentration and first-order in iodine concentration. Cyclopropane, C3H6, is a ring compound that undergoes ring rupture in the gas phase to form propene, as shown in equation (3).  (3) At certain pressures the rate of this reaction depends on the pressure of cyclopropane raised to the first power. The rate equation may be written R = k Pcyclopropane (4) This ring opening or isomerization is a first-order reaction. In addition to the type of second-order reaction described by equation (2), the rate of a reaction might be proportional to the concentration of a single reactant raised to the second power. For example, the decomposition of ozone, O3, to give oxygen as shown in equation (5), 2 O3(g) 3 O2(g) (5) follows the second-order rate equation R + k P2O3 (6) It is important to recognize that there is not necessarily a connection between the stoichiometric equation for the reaction and the kinetic order. Most chemical reactions, however, proceed by either first- or second-order rate laws or by sums of such rate laws. The rate for the reaction studied in this experiment: S2O3-2(aq) + 2H+(aq) H2O(l) + SO2(g) + S(s) (7) will probably have a fairly simple form such as R = k [S2O3-2]m[H+]n (8) The exponents m and n may be small whole numbers such as 0, 1, or 2, but could be negative or fractional numbers. The overall order for the reaction is the sum of the exponents, m plus n. Because the stoichiometric equation for the reaction between thiosulfate and hydrochloric acid does not give any information concerning the rate of the reaction, the order of the reaction must be determined from experimental data. If, in two successive experiments, the concentration of thiosulfate differs while the hydrogen ion concentration remains constant, the rate of reaction obtained from the two experiments will indicate the order of the reaction with respect to the concentration of thiosulfate. If there is no change in the rate of reaction in the two experiments, the reaction is zero-order in thiosulfate. If the rate doubles when the thiosulfate concentration is doubled, the reaction is first-order with respect to thiosulfate concentration. If the rate quadruples when the thiosulfate concentration is doubled, the reaction is second-order in thiosulfate. The rate of the reaction doubles if the elapsed reaction time is decreased by one-half. The rate quadruples if the elapsed reaction time of the second experiment is one-fourth that of the first experiment. In similar fashion, the order of the reaction with respect to the concentration of hydrogen ion can be found by changing the hydrochloric acid concentration while keeping the thiosulfate concentration constant (see study topic 1). A more quantitative expression for the determination of the reaction order can be derived. As above, two successive experiments are performed using thiosulfate concentrations [S2O3-2]1 and [S2O3-2]2, respectively. The hydrogen ion concentration, volume, and temperature are kept constant. Then from equation (8) R2 = k [S2O3-2]2m[H+]n (9) R1 = k [S2O3-2]1m[H+]n (10) Dividing equation (9) by equation (10) gives  (11) If the value of m is not readily apparent to you, it can be easily calculated by using the following relationship:  (12) A similar equation can be derived when the hydrogen ion concentration is varied and the thiosulfate concentration is held constant. It is necessary to calculate the concentration of the reactants in the initial reaction mixture when using the above-described method of determining kinetic order. Suppose the reaction mixture was prepared by mixing 5.00 ml of 2.00M hydrochloric acid solution, 30.0 ml of 0.200M sodium thiosulfate solution, and 20.0 ml of distilled water. The total volume of the reaction mixture is then assumed to be 55.0 ml. The concentration of either reactant may be found from the general equation (13). For each component, i, let Ms,i and Vs,i be the molarity and volume, respectively, of the stock solution used in preparing the reaction mixture. If the final volume of the reaction mixture is Vf, then the final concentration for component i, Mf,i, is Mf,i = F(molesf i,Vf) = F(Vs i Ms i,Vf) (13) For the specific case cited above, the concentration of thiosulfate in the reaction mixture would be found by A(Concentration of,Thiosulfate) = F(30.0 ml,55.0 ml) x 0.200M = 0.109M References 1. J. Olmsted III, G.M. Williams, Chemistry, The Molecular Science, Mosby, St. Louis, MO, 1994, pp. 647-699. 2. J.C. Kotz, K.F. Purcell, Chemistry & Chemical Reactivity, Second Edition, Saunders, Philadelphia, PA, 1991, pp. 607-649. 3. R.H. Petrucci, General Chemistry, Macmillan Publishing Company, New York, NY, 1989, pp. 527-568. PART I -Experimental Procedure Make up 500 ml of a 0.2 M Na2S2O3 solution. Use the Na2S2O3.5H2O from your synthesis. A balance which weighs to 0.1 g and a graduated cylinder or even the printed graduations on a 500 ml Erlenmeyer flask are of sufficient accuracy for this experiment. 1. Rate versus Concentration Place 50 ml of 0.2M Na2S2O3 solution into a 150 ml beaker. Place the beaker on a sheet of paper marked with an X (using a felt tipped marker). Quickly add 5 ml of 2M HCl and note the time. Swirl the contents of the beaker a few times to mix the reactants. Look down upon the top of the beaker. Record the amount of time required for the X to disappear completely. Repeat this procedure using 40, 30, 20, and 10 ml portions of Na2S2O3 solution, adding water in each case so that the total volume before adding HCl is 50 ml. Use a table in your lab book similar to Table 1. Table 1. Na2S2O3Na2S2O3WaterTime1/TimeSolution (ml)molarity (M)(ml)(sec)(sec-1)5004010302020301040 2. Rate versus Temperature Repeat the experiment using 20 ml of Na2S2O3 solution and 30 ml of water at about 10oC above and below room temperature. To heat the solution, place the 150 ml beaker filled with the thiosulfate solution into a 400 ml beaker filled with hot tap water. Record the temperature with a thermometer. Remove the 150 ml beaker, quickly wipe the bottom of the beaker with a towel, place it on the X, and proceed as before. Use ice water in the 400 ml beaker for the colder temperature. Calculations 1. The reaction rate is inversely proportional to the time it takes for the X to disappear. Determine the order of the reaction with respect to the concentration of thiosulfate from the data in Table 1. If the order is not close to an integer, you may have to solve for m by using equation (12). Use at least four ratios and report the average result. Alternatively, you may determine the order graphically. 2. Plot 1/Time versus temperature for your temperature data. From this curve predict how long the reaction should take at 4oC above the original temperature. Does this reaction follow the rule of thumb that the reaction rate doubles for an increase in temperature of 10oC? (A more complete analysis of the temperature dependence is performed in study 3.) PART II Decide which one of the three areas you are going to study. You must design your own experimental procedure. Here are some general comments which may help. Study 1 Extend the experiment outlined in PART I to determine the order of the reaction with respect to [H+]. Consider what the reaction times are likely to be and adjust the concentrations to keep the times reasonable. If the order of the reaction is not a simple integer, use the following approach: Assume that the rate law is in the form R = k[X]m Now take the log of both sides, log R = log k + m log[X] This equation is in the form of a straight line with slope m, so that a plot of log R, or equivalently log (1/Time), versus log [X] should yield a straight line with slope m. Cricket Graph is available to help you find the best slope. Ask the lab instructor to show you how to use the computer program, if necessary. Remember to report the correlation coefficient (R2) as an indicator of how well your data fit the model. Alternatively, you may determine the order by using ratios of data points and a form of equation (12). Study 2 Sodium sulfite (Na2SO3) is added to fixing baths to prevent the decomposition of the thiosulfate. Design a study to look at the effects of various concentrations of sulfite. A stock solution of 0.10M Na2SO3 will be available in the laboratory. Can you make sense out of your data? Try a data treatment similar to that discussed in study 1. Suggest a mechanism for the action of Na2SO3. Hint: Remember that in equation (7) SO2 is slightly soluble in water giving a solution of sulfurous acid. Study 3 Extend the temperature variation experiment from PART I to determine the activation energy for this reaction. Cricket Graph is available to help you find the best straight line through a set of data points and calculate the best slope. Use this program to analyze your data. But before you use the computer, graph your data in an appropriate manner and estimate the slope from your graph. Ask the lab instructor to show you how to use the computer program, if necessary. Remember to report the correlation coefficient (R2) as an indicator of how well your data fit the model. Hint: Recall, Rate = k[S2O3-2]m[H+]n. If [S2O3-2] and [H+] are constant, then: Rate = (constant)k. Report Present the results of your experiments from PART I in a table similar to Table 1. Include everything from the calculations section in your report, either handwritten or as a photocopy from your laboratory notebook; attach your graph. See the note on graphs below. For PA RT II, give a short, concise summary of your procedure and state your results. Include any graphs that you made. All graphs prepared manually should approximately fill a full sheet of graph paper. Axes should be clearly labeled and the units of your variables indicated. In your graphs remember to circle the data points and draw a smooth curve through the points; don't try to "connect the dots". If you used Cricket Graph for some of your graphs, be sure to enlarge them to approximately fill the page. Be sure to label axes appropriately and include the equation for the line and the R2 value. Include your partner's name on your report or indicate that you worked alone. Chemistry 142 RATE OF REACTION: THIOSULFATE DECOMPOSITION PRELABORATORY ASSIGNMENT Name 1. The reaction between A and B has the following stoichiometry: 2A + 2B  C + 2D The reaction is first-order in A and second-order in B. In a solution which is 0.20M in A and 0.10M in B the rate of formation of C is 1.0 x 10-4M sec-1. Calculate the rate constant. k = 2. Sulfur dioxide reduces HIO3 in aqueous acid according to the reaction 3SO2(g) + 3H2O(l) + HIO3(aq) 3H2SO4(aq) + HI(aq) The end of the reaction, when excess HIO3 is present, can be detected by adding starch to the solution  5HI(aq) + HIO3(aq)3I2(aq) + 3H2O(l) When the SO2 is gone, HI and HIO3 react rapidly, I2 is adsorbed on the starch and the suspension of starch turns dark blue. The data below were obtained from a series of such solutions: SO2 HIO3Reaction TimeM x 104M x 103sec14.63.6025.8 7.313.6052.214.67.2112.6 Determine the order of the reaction with respect to each of the reactants. order in SO2 HIO3 3. Calculate the weight of Na2S2O3.5H2O necessary to make 500 ml of 0.20 M Na2S2O3 solution. (over) 4. In PART II, outline the procedure you would use for: (Work out a scheme for each study, even though you will do only one in lab. For each of these studies a data plot is necessary. Label the axes with the quantities to be plotted. Draw in a straight line using your prediction for the sign of the slope. Clearly label which of these studies you plan to perform in the lab.) Study 1  Study 2  Study 3  -- v d WORD "`""   ` ɠ p   (0(r0(b0 HH#CSU #CSU"/md load /bu known {bu} if /md load /fc known {fc} if %%BeginResource: procset mdl_dict /mdl_dict 100 dict def mdl_dict begin /bd{bind def}bind def /xdf{exch def}bd /xs{exch store}bd /ld{load def}bd /Z{0 def}bd /T/true /F/false /:L/lineto /lw/setlinewidth /:M/moveto /rl/rlineto /rm/rmoveto /:C/curveto /:T/translate /:K/closepath /:mf/makefont /gS/gsave /gR/grestore /np/newpath /cp/currentpoint /slc/setlinecap /S/show 17{ld}repeat /G where not { /G/setgray ld } { pop }ifelse /:F where not { /:F/setrgbcolor ld }{ pop } ifelse /:m where not { /:m { gS 0 0.1 rm 0.067 lw 0 rl stroke gR } bd } { pop } ifelse /:J { dup stringwidth pop exch 5 1 roll sub 10 mul 3 1 roll 10 mul add div dup 10 div 3 2 roll 0.0 32 4 2 roll 0.0 exch awidthshow }bd /:A { dup stringwidth pop exch 4 1 roll sub exch div exch 0.0 exch ashow } bd /rectclip where { pop/rC/rectclip ld }{ /rC { np 4 2 roll :M 1 index 0 rl 0 exch rl neg 0 rl :K clip np }bd }ifelse /rectfill where { pop/rF/rectfill ld }{ /rF { gS np 4 2 roll :M 1 index 0 rl 0 exch rl neg 0 rl fill gR }bd }ifelse /rectstroke where { pop/rS/rectstroke ld }{ /rS { gS np 4 2 roll :M 1 index 0 rl 0 exch rl neg 0 rl :K stroke gR }bd }ifelse /mdl_A_fill (AAAA) def /mdl_A_pat {<0102040810204080>} def /mdl_B_fill (BBBB) def /mdl_B_pat {<40FF404040404040>} def /mdl_C_fill (CCCC) def /mdl_C_pat {<8041221408142241>} def /mdl_D_fill (DDDD) def /mdl_D_pat {<8040201008040201>} def /mdl_E_fill (EEEE) def /mdl_E_pat {<00FF000000000000>} def /mdl_F_fill (FFFF) def /mdl_F_pat {<4040404040404040>} def gS initmatrix /mdl_xdev 72.0 0.0 dtransform pop def /mdl_ydev 0.0 72.0 dtransform exch pop def gR /mdl_xmul mdl_xdev 72.0 div round 72.0 mul 8.0 mul mdl_xdev div def /mdl_ymul mdl_ydev 72.0 div round 72.0 mul 8.0 mul mdl_ydev div def /mdl_patdict 33 dict def mdl_patdict begin /FontType 3 def /FontMatrix [1 0 0 1 0 0] def /FontBBox [0 0 1 1] def /Encoding StandardEncoding def /CharProcs 27 dict def CharProcs begin /A {8 8 true [8 0 0 -8 0 8] mdl_A_pat imagemask} def /B {8 8 true [8 0 0 -8 0 8] mdl_B_pat imagemask} def /C {8 8 true [8 0 0 -8 0 8] mdl_C_pat imagemask} def /D {8 8 true [8 0 0 -8 0 8] mdl_D_pat imagemask} def /E {8 8 true [8 0 0 -8 0 8] mdl_E_pat imagemask} def /F {8 8 true [8 0 0 -8 0 8] mdl_F_pat imagemask} def end /BuildChar { 1 0 0 0 1 1 setcachedevice exch begin Encoding exch get CharProcs exch get end exec } bd end /mPatFnt mdl_patdict definefont pop /mVcGd F def /vKvcm { /mVcGd F def } bd /mTM matrix def /mBus matrix def /mVcM matrix def /mVS F def /mVO { mVcGd mVS not and { mBus currentmatrix pop mVcM setmatrix /mVS T def } if } bd /mVF { mVS { mBus setmatrix /mVS F def } if } bd /mCrtVirt { 0 begin gS mVF /bbox 4 array def /pbox 4 array def /smx matrix def /tmx matrix def bbox astore pop np :M :L pathbbox pbox astore pop pbox 2 get pbox 0 get sub bbox 2 get bbox 0 get sub div /sx exch def pbox 3 get pbox 1 get sub bbox 3 get bbox 1 get sub div /sy exch def sx sy smx scale pbox 0 get sx div bbox 0 get sub pbox 1 get sy div bbox 1 get sub tmx :T exch matrix concatmatrix matrix currentmatrix mVcM concatmatrix pop gR end /mVcGd T def } bd /mCrtVirt load 0 6 dict put /mDshAry [ [] [24 16] [8 32] [24 16 4 16] [8 4] ] def /languagelevel where {pop languagelevel} {1} ifelse 2 ge { /mSLe { 1 slc true setstrokeadjust } bd } { /mSLe { 1 slc } bd } ifelse /mSL { lw mSLe } bd /mSC/setrgbcolor ld /mSD { dup 0 gt { 0 slc } if mDshAry exch get 0 setdash } bd /mPatFl { mVF gS clip 2 dict begin /fillstr exch def /mPatFnt findfont mdl_xmul mdl_ymul matrix scale :mf setfont initmatrix pathbbox mdl_xmul div ceiling mdl_xmul mul 4 1 roll mdl_ymul div ceiling mdl_ymul mul 4 1 roll mdl_xmul div floor mdl_xmul mul 4 1 roll mdl_ymul div floor mdl_ymul mul 4 1 roll 2 index sub mdl_xmul div ceiling cvi exch 3 index sub mdl_ymul div ceiling cvi exch 4 2 roll :M {gS dup fillstr length idiv {fillstr show} repeat dup fillstr length mod fillstr exch 0 exch getinterval show gR 0 mdl_ymul rm} repeat pop end gR np mVO } bd /mClp { initclip rC } bd /mFC { initclip } bd /mOFlP { gS :F fill gR gS :F mPatFl gR stroke } bd /mFlP { gS :F mPatFl gR stroke } bd /mL { :M rl stroke } bd /mRE { gS :F rF gR } bd /mRF { gS rS gR } bd /mRP { np 4 2 roll :M 1 index 0 rl 0 exch rl neg 0 rl :K } bd /mPLP { :M { rl } repeat } bd /mCPLE { gS :F mPLP :K fill gR } bd /mCPLF { gS mPLP :K stroke gR } bd /mPLF { gS mPLP stroke gR } bd /mOvlP { mTM currentmatrix pop np :T scale 0 0 1 0 360 arc :K mTM setmatrix } bd /mOvlE { gS :F mOvlP fill gR } bd /mOvlF { gS mOvlP stroke gR } bd /mRRP { 0 begin /centerY exch def /centerX exch def /scaleY exch def /scaleX exch def /dY exch def /dX exch def /pX 5 array def /pY 5 array def pX 0 dX neg put pY 0 0 put pX 1 dX neg put pY 1 dY neg put pX 2 dX put pY 2 dY neg put pX 3 dX put pY 3 dY put pX 4 dX neg put pY 4 dY put pX {scaleX div} forall pX astore pop pY {scaleY div} forall pY astore pop mTM currentmatrix pop np centerX centerY :T scaleX scaleY scale pX 0 get pY 0 get :M 4 -1 1 {3 {dup} repeat pX exch get exch pY exch get 3 -1 roll 1 sub pX exch get 4 -1 roll 1 sub pY exch get .5 arcto 4 {pop} repeat} for end :K mTM setmatrix } bd /mRRP load 0 9 dict put /mRRE { gS :F mRRP fill gR } bd /mRRF { gS mRRP stroke gR } bd /mArcP { mTM currentmatrix pop np |:T scale 0 0 1 5 -2 roll arc mTM setmatrix } bd /mAF { gS mArcP stroke gR } bd end %%EndResource /md load /bn known {bn} if , Symbol .( , Monaco ) /sf_sav /sf load def /sf { sf_sav /sfx true def } def /gR_sav /gR load def /gR_del { sfx { /gR /gR_sav load def gS gR }{ gR_sav } ifelse } def /gRx { gRif { /gR /gR_del load def /sfx false def } if } def /gRy { gRif { gR } if } def /gRq { ucurrentfont /FontName get eq not /gRif exch def } def mdl_dict begin mFC 2 setmiterlimit 0 mSL 0. 0. 0. mSC 0 mSD gS end " ,  Helvetica(Њ /Helvetica gRq "8gR mdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD mVO mVF "#Ccp "SUcp 370 50 3112 530 mCrtVirt 'swsDXY Timesx 0! Genevax D C%!! Genevax DTC%!! Genevax D/C%! '* '* '* 9 X!"9 DT 9 T9  0! Genevax EC%!! Genevax EC%! '(! Genevax E(C%! '  9r]Y0=0=(g):fx:fT@հ:f   @  (^]Y-E:T-E:T(g):f4:f0@հ:f8   @, Geneva (JRCend "JZgRx x( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 521 440 :M (C)S mVO mVF end gRy "( (JEHgRx x( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 386 440 :M (H)S mVO mVF end gRy # (OM2gRx P( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 469 490 :M (2)S mVO mVF end gRy " (JoCgRx x( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 809 440 :M (C)S mVO mVF end gRy "( (JwHgRx x( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 887 440 :M (H)S mVO mVF end gRy # (O2gRx P( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 970 490 :M (2)S mVO mVF end gRy " (1`CgRx x( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 663 190 :M (C)S mVO mVF end gRy "( (1hHgRx x( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 741 190 :M (H)S mVO mVF end gRy # (6q2gRx P( Imdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 824 240 :M (2)S mVO mVF end gRy "Fmdl_dict begin mVF mVO 0 0 0 mSC 7.2 mSL 0 mSD 172.8 0 617.2 381.2 mL "D\52.8 -96 605.2 302 mL "<Z55.2 96 746.8 206 mL "3i 0 mSL 374.4 0 1368.4 290 mL ";%-67.2 -36 1430.8 323.6 mL ">379.2 0 1363.6 239.6 mL "6&-67.2 -36 1742.8 239.6 mL # (?C mVO mVF end "?gRx x( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 2073 330 :M (C)S mVO mVF end gRy "( (?HgRx x( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 1938 330 :M (H)S mVO mVF end gRy # (D2gRx P( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 2021 380 :M (2)S mVO mVF end gRy " (? CgRx x( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 2361 330 :M (C)S mVO mVF end gRy "( (?HgRx x( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 2439 330 :M (H)S mVO mVF end gRy #Emdl_dict begin mVF mVO 0 0 0 mSC 7.2 mSL 0 mSD 170.4 0 2170 287.6 mL ";170.4 0 2170 251.6 mL "7 (?'C mVO mVF end "?/gRx x( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 2649 330 :M (C)S mVO mVF end gRy "( (?/HgRx x( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 2727 330 :M (H)S mVO mVF end gRy # (D73gRx P( Jmdl_dict begin mVF mVO 0 0 0 mSC 0 mSL 0 mSD 2810 380 :M (3)S mVO mVF end gRy "Fmdl_dict begin mVF mVO 0 0 0 mSC 7.2 mSL 0 mSD 91.2 0 2537.2 270.8 mL "9 mVO mVF end # 5C25A,Times (>(g)gR gS  3EAU23?(<F(g)gR gS  #CSU"KF# d WORD "`""   ` ɠ p    d WORD "`""   ` ɠ p   1*m1*m1z xy"zm*ġcurrentpoint 192837465 #֠ġ currentpoint  z"p ġsave/chemsave exch def 4%%BeginProcSet: chemdict 24 4 % ChemDraw Laser Prep [% CopyRight 1986-1988, Cambridge Scientific Computing, Inc. userdict/chemdict 190 dict put cchemdict begin/version 24 def/sv 4 def/b{bind def}bind def/L{load def}b/d/def L/a/add L/al/aload L \/as/astore L/at/atan L/cp/closepath L/cv/curveto L/cw/currentlinewidth L/cpt/currentpoint L a/dv/div L/D/dup L/e/exch L/F/false L/f/fill L/fa/forall L/g/get L/gi/getinterval L/gr/grestore L b/gs/gsave L/ie/ifelse L/ix/index L/l/lineto L/mt/matrix L/M/moveto L/m/mul L/n/neg L/np/newpath L [/pb/pathbbox L/P/pop L/r/roll L/rm/rmoveto L/ro/rotate L/rp/repeat L/ru/round L/sc/scale L ]/sg/setgray L/sl/setlinewidth L/sm/setmatrix L/st/stroke L/sp/strokepath L/sq/sqrt L/s/sub L _/T/true L/tr/transform L/xl/translate L/xc/exec L/S{sf m}b/dL{[3 S] D 0 3 cw m put 0 setdash}b ]/sf 20 d/cR 12 d/wF 1.5 d/aF 12 d/aR 0.25 d/aA 45 d/hS 2.7 S d/o{1 ix}b/rot{3 -1 r}b/x{e d}b H/CMT mt d/TM mt d/SM{CMT sm}b/s1 1 string d/fp{T charpath flattenpath}b \/p{tr ru 0.25 a e ru 0.25 a e itransform}b/db{array/bs x/N 0 d}b/B{bs N rot put/N N 1 a d}b ?/SpA{gs np o o xl rot s e rot s o 0 ne o 0 ne or{at ro}{P P}ie PaR aL m n D aL a 0 p M 0 o n aA n aA arc cp f gr}b/Sp{/St x 0.4/aR x 35/aA x gs WaF lW m 0.7 m St 4 and 0 ne{2 m bW sl}if/aL x St 8 and 0 ne{8 ix 8 ix 3 ix 3 ix SpA}if USt 16 and 0 ne{2 ix 6 m 1 a D ix e D ix e D ix e D ix e P SpA}if St 2 and 0 ne{dL}if "np M{cv}rp st gr}b/Ha{gs np 3 1 r Cxl D sc -.6 1.2 p M 0.6 1.2 p l -.6 2.2 p M 0.6 2.2 p l SM st gr}b ?/OP{3 ix 3 ix xl 3 -1 r s 3 1 r e s o o at ro D m e D m a sq}b 4/OB{/bS x OP D bS dv D lW 2 m lt{P lW 2 m}if/bd x}b 7/DA{np 0 0 M aL 0 aR aL m 180 aA s 180 aA a arc cp f}b L/OA{np 0 cw -2 dv M aL 0 aR aL m 180 aA s 180 arc 0 cw -2 dv rlineto cp f}b ^/SA{aF m lW m/aL x 0.25/aR x 45/aA x aL 1 aR s m np 0 p M rad 0 p l gs SM cw 0.8 m sl st gr}b _/CA{aF lW m 0.7 m/aL x 0.4/aR x 35/aA x aL 1 aR s m 2 dv rad D m o D m s D 0 le{P P P}{sq at 2 Vm np rad 0 rad 180 6 -1 r s 180 6 -1 r s arc gs SM cw 0.8 m sl st gr cpt e at ro}ie}b 4/AA{np rad 0 rad 180 180 6 -1 r a arc gs SM st gr}b ]/RA{lW m/w x np rad w p M w .7 dv w p l rad w n p M w .7 dv w n p l w .35 dv w 2 m p M 0 0 p l w .35 dv w -2 m p l st}b L/HA{lW m/w x np 0 0 p M w 2 m D p l w 2 m w p l rad w p l rad w n p l w 2 m V w n p l w 2 m D n p l cp st}b/Ar1{gs 5 1 r OP/rad x{{2.25 SA DA}{1.5 SA DA}{1 SA DA} ]{lW 4 m sl 4.5 SA DA}{lW 4 m sl 3 SA DA}{lW 4 m sl 2 SA DA}{270 CA DA}{180 CA DA}{120 CA DA} T{90 CA DA}{2.5 RA}{2.5 HA}{1 -1 sc 270 CA DA}{1 -1 sc 180 CA DA}{1 -1 sc 120 CA DA} _{1 -1 sc 90 CA DA}{5 RA}{5 HA}{dL 2.25 SA DA}{dL 1.5 SA DA}{dL 1 SA DA}{2.25 SA OA}{1.5 SA OA} c{1 SA OA}{1 -1 sc 2.25 SA OA}{1 -1 sc 1.5 SA OA}{1 -1 sc 1 SA OA}{270 CA OA}{180 CA OA}{120 CA OA} V{90 CA OA}{1 -1 sc 270 CA OA}{1 -1 sc 180 CA OA}{1 -1 sc 120 CA OA}{1 -1 sc 90 CA OA} ^{1 -1 sc 270 AA}{1 -1 sc 180 AA}{1 -1 sc 120 AA}{1 -1 sc 90 AA}}e g xc gr}b/ac{arcto 4{P}rp}b &=JL>?EF(* R S ? @ t u y z } ~        $ % & ' 0 1 Jb`  Ja @9  J8   N ./01345<=>?ABC67<Y\be14>ALOQRZ]_bde;FiDU @ @@ @ @c@  T"&'()*+./0123qs  !!####$e$f%f%m%%&&(()%),)@)A)C)D))))******+"+),E,L-9-:--------@@  ^-------------0#0)0E0K1G1H1111222P2Q222233!3A3B3s3t3|3}3333333333444#4$4&4'40414C4D4X4Y4j4k45 5 55$5%5,5-55555555555 J J  J, @  Q5555556 6!6"6#6$6%6677778888888? @@ @ @H @ <=JKcd 45u O P \   S T k l A B s t STz{ﯩ $4$ $ $$$ $3 $J$h$  $2 $ h$ h$ $ $ $<12ABIJ9:qr-./0123456789:;F1#$,4:?FŽ  $ h$ h$ $ hh$ h$ h$$ $.$ $-$ 3FGUbgmuvyz|}~!!!!#T#U$$$%e%f%n&&׺ $2$ h $4h$ h $Jh$ h  (P@P$@@@@@@@@@@@@@@@@@@@@@6&&&&'')$)%)-+!+"+*---.111111222C2D2Y2Z333"3#3m3n334 4 444647445 555ߟzP(P("@@@@@@@@@@@@ 8 $  P$@ $  $$$ $  $V$  $d$  $J$h$ /55&5.5253585=5B5C5J5O5T5U5Z5_5d5e5f5555556;6>6?6@6A6B6C6D6W6X6677777777888888Ȼȶȶȶ$$ $ h$ $ P(P("@@@@@@@@@@@@ 8  81   78 #05X7?-9  -5?ghijkF&58lmnop !"V&p&r9:]:^:_:` HH(EG(HH(d'@=/R@H-:LaserWriter 8 Times5X5X 5X*'=E ^Rate of reaction- CH142 '95CH142 Jane House96 general,lab,kinetics,thiosulfate Jane House