Experiment 24: A Rate Law And Activation Energy
Experiment 24 - A Rate Law and Activation Energy
Observe
• To conduct an experiment in order to discover and calculate the expression known as the rate law for a particular reaction.
• To conduct an experiment in order to determine the role each reactant plays within the reaction and the overall activation energy that is needed for a chemical reaction to occur all while utilizing an analytical tool.
Procedure
1. Determination of Reaction Rates
• Obtain boiled, deionized water, pipets or burets, and 20-mL beakers or 150 mm test tubes in order to mix solutions for 8 kinetic trials.
• Make sure to measure the volumes of potassium iodide and sodium thiosulfate with pipets before adding them to the test tubes or the beakers.
• For Trial #4, acquire
solution A (containing potassium iodide and sodium thiosulfate) prepared earlier and stir the solution in a small beaker or a test tube. Create solution B by utilizing a pipet to add 3 mL of 0.1 M hydrogen peroxide into a clean beaker (10 mL) or a test tube.
• In order for the reaction to take place, solution B must be mixed in with solution A as shown in Figure 24.2. Make sure to keep everything clean and do not wipe the glassware with any form of paper products.
• Add solution B into the beaker or test tube containing solution A and begin timing. Stir the solution only once and notice the deep-blue color change within the solution (use a white sheet of paper in order to witness a more accurate color change).
• Once the mixture turns a deep-blue shade, stop the time and record the data collected.
• Continue to mix and record the time of the other 7 kinetic trials. Make sure to discard the solutions in the properly marked container.
2. Calculations for Determining the Rate Law
• Compute and document various different calculations for each kinetic trial conducted.
• Make sure to calculate the moles of thiosulfate absorbed in each kinetic trial conducted. Also, calculate the reaction rates and logarithms for each kinetic trail and record the calculations.
• Continuing with the calculations, compute the initial molar concentration with the logarithm for iodide utilized for each trial. Finally, calculate the initial molar concentration and logarithm for hydrogen peroxide associated with each trial.
3. Determination of the Reaction Order, p and q, for Each Reactant
• Plot the data collected for constant hydrogen peroxide concentration using a graph paper or an analytical tool in order to determine p. Trials 1,2,3 and 4 have the same peroxide concentration. Make sure to connect the dots by drawing a straight line through the points and calculate the slope of the line.
• Plot the data collected the iodide concentration using a graph paper or an analytical tool in order to determine the q. Trials 1,5,6,7 all have the same concentration. Make sure to draw a straight line through the dots plotted and compute the slope of the line.
4. Determination of k’, the Specific Rate Constant for the Reaction
• Prepare two additional solutions for created in Trial 4 using 150-mm test tubes. Place one set of the solutions in an ice bath while the other one in a warm bath (35° C) for 5 minutes until equilibrium is achieved.
• After stability has been established add Solution B into Solution A and start the clock. Make sure to stir the mixture. Once the deep-blue color becomes visible stop the clock. Record the data collected as in the time and the temperature of the water bath. Repeat the experiment for accuracy.
• Compute and record the reaction rates for the two trials using different temperatures. Re-compute the reaction rate from the first experiment conducted for Trial 4. Using the reaction rates from the three different temperatures and the rate law calculated earlier in order to determine the k’.
• Calculate the logarithms for these constant rates. Plot the k’ and 1/T (K) for the three trials and make sure to discern the slope for the data plotted and the activation energy for the overall reaction.
Observe
• To conduct an experiment in order to discover and calculate the expression known as the rate law for a particular reaction.
• To conduct an experiment in order to determine the role each reactant plays within the reaction and the overall activation energy that is needed for a chemical reaction to occur all while utilizing an analytical tool.
Procedure
1. Determination of Reaction Rates
• Obtain boiled, deionized water, pipets or burets, and 20-mL beakers or 150 mm test tubes in order to mix solutions for 8 kinetic trials.
• Make sure to measure the volumes of potassium iodide and sodium thiosulfate with pipets before adding them to the test tubes or the beakers.
• For Trial #4, acquire
solution A (containing potassium iodide and sodium thiosulfate) prepared earlier and stir the solution in a small beaker or a test tube. Create solution B by utilizing a pipet to add 3 mL of 0.1 M hydrogen peroxide into a clean beaker (10 mL) or a test tube.
• In order for the reaction to take place, solution B must be mixed in with solution A as shown in Figure 24.2. Make sure to keep everything clean and do not wipe the glassware with any form of paper products.
• Add solution B into the beaker or test tube containing solution A and begin timing. Stir the solution only once and notice the deep-blue color change within the solution (use a white sheet of paper in order to witness a more accurate color change).
• Once the mixture turns a deep-blue shade, stop the time and record the data collected.
• Continue to mix and record the time of the other 7 kinetic trials. Make sure to discard the solutions in the properly marked container.
2. Calculations for Determining the Rate Law
• Compute and document various different calculations for each kinetic trial conducted.
• Make sure to calculate the moles of thiosulfate absorbed in each kinetic trial conducted. Also, calculate the reaction rates and logarithms for each kinetic trail and record the calculations.
• Continuing with the calculations, compute the initial molar concentration with the logarithm for iodide utilized for each trial. Finally, calculate the initial molar concentration and logarithm for hydrogen peroxide associated with each trial.
3. Determination of the Reaction Order, p and q, for Each Reactant
• Plot the data collected for constant hydrogen peroxide concentration using a graph paper or an analytical tool in order to determine p. Trials 1,2,3 and 4 have the same peroxide concentration. Make sure to connect the dots by drawing a straight line through the points and calculate the slope of the line.
• Plot the data collected the iodide concentration using a graph paper or an analytical tool in order to determine the q. Trials 1,5,6,7 all have the same concentration. Make sure to draw a straight line through the dots plotted and compute the slope of the line.
4. Determination of k’, the Specific Rate Constant for the Reaction
• Prepare two additional solutions for created in Trial 4 using 150-mm test tubes. Place one set of the solutions in an ice bath while the other one in a warm bath (35° C) for 5 minutes until equilibrium is achieved.
• After stability has been established add Solution B into Solution A and start the clock. Make sure to stir the mixture. Once the deep-blue color becomes visible stop the clock. Record the data collected as in the time and the temperature of the water bath. Repeat the experiment for accuracy.
• Compute and record the reaction rates for the two trials using different temperatures. Re-compute the reaction rate from the first experiment conducted for Trial 4. Using the reaction rates from the three different temperatures and the rate law calculated earlier in order to determine the k’.
• Calculate the logarithms for these constant rates. Plot the k’ and 1/T (K) for the three trials and make sure to discern the slope for the data plotted and the activation energy for the overall reaction.