Kinetics of the persulfate iodide clock reaction. Experiment 4: Kinetics Of The Persulfate 2022-10-10
Kinetics of the persulfate iodide clock reaction Rating:
The persulfate-iodide clock reaction is a classic chemical kinetics experiment that demonstrates the concept of a rate-determining step and the effect of various factors on the rate of a chemical reaction. In this reaction, a solution of potassium persulfate (K2S2O8) and sodium iodide (NaI) is mixed together and the time it takes for the solution to change color is measured. The reaction can be written as follows:
2K2S2O8 + 2NaI -> 2K2SO4 + I2 + 2Na2SO4
The key feature of this reaction is that it proceeds through a series of intermediate steps, rather than occurring all at once. The first step is the slowest, or rate-determining step, and controls the overall rate of the reaction. This step involves the formation of intermediate species known as iodide ions (I-) and persulfate ions (S2O8^2-).
The rate of the persulfate-iodide clock reaction is affected by a number of factors, including the concentration of the reactants, the temperature, and the presence of catalysts. Increasing the concentration of the reactants will generally increase the rate of the reaction, since there are more reactant molecules present to collide and react. Similarly, increasing the temperature will also increase the rate of the reaction, as the increased kinetic energy of the reactant molecules will make it more likely that they will successfully collide and react.
Catalysts can also affect the rate of the persulfate-iodide clock reaction. A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. In the persulfate-iodide clock reaction, a variety of substances can act as catalysts, including certain metals and organic compounds. These catalysts work by providing an alternative pathway for the reaction to proceed through, which can be faster than the uncatalyzed reaction.
In summary, the persulfate-iodide clock reaction is a useful tool for demonstrating the concept of a rate-determining step and the effect of various factors on the rate of a chemical reaction. By carefully controlling the conditions of the reaction, it is possible to gain a better understanding of the underlying kinetics and mechanisms involved in the reaction.
Experiment 4: Kinetics Of The Persulfate
Figure 3 The components of the solution. Theoretical values with respect to potassium iodide and sodium persulfate are both 1. The procedures were repeated to the different volumes of the S 2O82- and Isolutions specified in the laboratory manual. The computed over-all order of the reaction is far from the theoretical value which is 2. A Kinetic Study of Potassium Iodide with Potassium Persulfate using Iodine Clock Reaction.
The flask was gently swirled and the time was recorded when the resulting solution turned to blue. Identify sources of error in the experiment and estimate their magnitude. Keywords: Chemical kinetics; Iodine clock reaction; Arrhenius plot; Rate equations Several methods and strategies can be used to investigate chemical reaction kinetics and for this type of reaction, iodine clock reaction was used. Errors may be caused due to contamination of the sample solutions. Delas Llagas Date Performed: March 11, 2014 3ChE-A Group No. A textbook of physical chemistry.
And the slope from the graph of potassium iodide is 0. Find the concentration of the two reagents iodide and persulfate used in each run Hint: what dilutions have occurred? As soon as all of the S2O3 2- ions are consumed, the excess iodine produced in 5 is free to react with starch, turning the solution blue 7. The contents of the beaker were then poured to the flask. This factor can be studied by varying the concentration of the reactants in a systematic manner. The iodine produced is immediately consumed by the added thiosulfate ions, and the excess iodine, which the thiosulfate failed to consume, causes the sample to change its color from clear to blue. Starch solution cm 3 5 5 5 5. Delas Llagas Date Performed: March 11, 2014 3ChE-A Group No.
Varying the concentrations of the reagents allows the rate equation to be determined and performing the experiment at different temperatures allows the activation energy to be determined. They are defined by the mechanism of the reaction, which is an account of the actual steps by which the molecules combine, and these orders can only be determined experimentally. If it is neutral, then there will be no changes observed on the rate of the reaction. In this experiment two colorless solutions are put together, at first there will be no visible reaction. For each run of the reaction, make up glassware as shown in the chart below. A logarithmic plot of the reaction rate against concentration shows a linear relationship in both cases with a positive gradient which shows that the rate of reaction increases with increasing concentration. Oliveira and Roberto B.
A kinetic study of potassium iodide with potassium persulfate using iodine clock reaction
Answers to Questions a. . Comment on the effect of the reduction in ionic strength on the rate of reaction and determine whether the reactants which form the activated complex have charges of the same or different sign. Both test tubes were put into a water bath afterwards for 10 minutes. Figure 2 Experimental Set up for the determination of effect of temperature Effect of ionic Strength Solutions of NH4 2S2O8 and 0. If the mixture changed its color upon the addition of solutions a and b to solutions c and d , a decrease in the amount of NH4 2S2O8 solution and increase of the amount of Na2S2O3 solution by 1 mL is advised. Comment on the effect of the reduction in ionic strength on the rate of reaction and determine whether the reactants which form the activated complex have charges of the same or different sign.
Make sure to give the units for k. When the product is positive an increase in the rate would be expected and if the product is negative a decrease would be expected. A known amount of thiosulfate ions will be added to the reaction vessel which will in turn consume iodine as it is produced. The charges of ions are also related to its ionic strength. Laboratory coat and eye protection are mandatory at all times. Record the "Blue Time" the time in seconds needed for the solution to turn blue for each run.
The flask was gently swirled and the time was recorded when the resulting solution turned to blue. Data and results: Table 1 Compositions of the solutions Solution M NH4 2S2O8 0. The experimental set up is illustrated in figure 2. Chemical Kinetics: Fundamentals and Recent Developments. Based on the data gathered and computed results the slope from the graph of sodium per sulfate is 10. When iodide reacts with persulfate ions, the reaction produces iodine and sulfate.
Identify sources of error in the experiment and estimate their magnitude. Int J Chem Sci. The charges of ions are also related to its ionic strength. The potential causes of the contamination are the chemical reagents may not be properly sealed in the storage. A few drops of starch. Treatment of Results: Determination of rate constant.
On the other hand. In this experiment two colorless solutions are put together, at first there will be no visible reaction. A few drops of starch, and a second solution containing 5 mL of solution c and 10 mL of solution d were added to the test tubes. Conclusion and recommendations: Conclusion: The experiment successfully demonstrated the reaction between iodide and persulfate. Adding the two the over-all order of the reaction based on the experiment was 11. Both test tubes were put into a water bath afterwards for 10 minutes.
Conclusion For this study, I utilized the iodine clock reaction between iodide ion and persulfate ion to determine the order of reaction with respect to iodide ion and persulfate ion and it was found to be 1, which is reported in most literatures. Use MSDS sheets and the full COSHH assessment forms to fill in this form. Catalytic processes in industry. Determining the Activation Energy. Recommendations: It is recommended to start from the last solution to check if a change in color will occur within 30 minutes time span. Chemical Engineering and Processing-Process Intensification.