y=mx+b Thus,a plot of Ink(y axis)versus 1/T(x axis)gives a straight line with a slope equal to-Ea/R and a y intercept equal to In 4. In this experiment.we will determine the kinetic parameters of the reaction between iodide metal cationsact as catalysts in reactions,largely because they canexist different oxidation states.They can easily gain an election from one reactant and pass it on to another.The effect of the catalyst will be calculated by comparing runs with identical concentrations and temperatures,with and without the catalyst.Catalysts are very important in industrial applications,as they can greatly speed up a process or allow it to run at lower temper tures or pressure The main difficulty in performing a kinetics experiment is to devise a means by which to measure the rate of the reaction,that is,a way to signal when the reaction has progressed to a certain point.If this can be done accurately,then the SOwill be constant In that case. all we need todo it is measure the time it takesfor each rial toreach that pont. The reaction sequence in this experiment is 31 +S2O))+2S0 (1) Ivm +2S0 3+S.O (2) Starch+Starch-licomplex (3) Reaction2 occurs as long as thiosulfate (SO is present in solution.It reacts with the triiodide ions produced in Reaction I and converts them back to iodide.When the thiosulfate is used up.triiodide will start to accumulate and Reaction curs,producing a dark blue some time interva )thereisngin cormn (Shas reached the desired level.Since the same amount of thiosulfate is added toeachrun the same amount of peroxydisulfate is used up in each run,making A constant for all runs.Since rate=ASO/Atime,if two runs have similar times,their times indicate faster rates. Experimental Procedure PDF文件使用"pdfFactory Pro”试用版本创建wm,fineprint,com,cny = + mx b Thus, a plot of ln k (y axis) versus 1/T (x axis) gives a straight line with a slope equal to –Ea/R and a y intercept equal to ln A. In this experiment, we will determine the kinetic parameters of the reaction between iodide and peroxydisulfate. We will also examine the effect of a catalyst on the rate of the reaction. Many metal cations act as catalysts in reactions, largely because they can exist in solution in two or more different oxidation states. They can easily gain an election from one reactant and pass it on to another. The effect of the catalyst will be calculated by comparing runs with identical concentrations and temperatures, with and without the catalyst. Catalysts are very important in industrial applications, as they can greatly speed up a process or allow it to run at lower temperatures or pressures. The main difficulty in performing a kinetics experiment is to devise a means by which to measure the rate of the reaction, that is, a way to signal when the reaction has progressed to a certain point. If this can be done accurately, then the 2 D S O2 8 - é ù ë û will be constant. In that case, all we need to do it is measure the time it takes for each trial to reach that point. The reaction sequence in this experiment is - 2 - 2 (aq) 2 8 (aq) 3(aq) 4 (aq) 3I +S O I 2SO - - + (1) - 2 - 2 3(aq) 2 3 (aq) (aq) 4 6 (aq) I +2S O 3I S O - - + (2) - - S (aq) 3(aq) 3 tarch +I Starch-I complex (3) Reaction 2 occurs as long as thiosulfate ( ) 2 S O2 3 - is present in solution. It reacts with the triiodide ions produced in Reaction 1 and converts them back to iodide. When the thiosulfate is used up, triiodide will start to accumulate and Reaction 3 occurs, producing a dark blue starch-complex. Thus, two colorless solutions will be mixed together, and at some time interval (15 seconds to 4 minutes), there is a sharp change in color from clear to dark blue, indicating that ( ) 2 S O2 8 - has reached the desired level. Since the same amount of thiosulfate is added to each run, the same amount of peroxydisulfate is used up in each run, making 2 D S O2 8 - é ù ë û constant for all runs. Since 2 2 8 rate D D S O / time - = é ù ë û , if two runs have similar times, their times indicate faster rates. Experimental Procedure PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.com.cn