Effect of Temperature on the Activation Energy

Effect of Temperature on the Activation EnergyTitle Investigating the Effect of Temperature on the Activation Energy training A. HypothesisI predict that as temperature rises, the faster are the rates of reaction. The reaction that will be studied in this experiment is betwixt milligram and sulfuric acid. This reaction is shown in the chemical equation down the stairsMg (s) + H2S04 (aq) MgS04 (aq) + H2 (g)In this experiment, 0.4 grams of milligram palm tree will be used, together with 100 cubiform cen mters of sulphuric acid which is in excess. The variable that I will be changing is the temperature of the water baths where the reactants (sulphuric acid and magnesium ribbon) will be placed. The heap of the throttle valve (hydrogen suck) to be collected at individually varying water bath temperature is 100 cubic centimeters. The time it takes for to collect 100 cubic centimeters of the hydrogen catalyst will be mea authenticd to calculate the rate of reaction.B. Backgrou ndThe fundamental basis of the collision theory is the kinetic theory which describes the state of matter in terms of the power of its particles, (Energex, 2006). According to Wilbraham and others (1997), the kinetic theory says that the tiny particles in every(prenominal) forms of matter are in constant motion. When heated, the particles of the substance absorb energy, well-nigh of which is stored within the particles. This stored energy does non raise the temperature of the substance. The rest of the energy goes into speeding up the particles. Particles lacking the necessary kinetic energy to react still shake up but simply bounce back. Substances decompose to simpler forms, or form new substances when supplied with sufficient energy, called the energizing energy. The activation energy is a barrier or an obstacle that the reactants must cross in order to decompose into simpler substances, or to combine and form new products.At higher temperatures, the particles of a substan ce exit faster and become more energetic. Thus, increasing temperatures help speed up the reaction by inaugural increasing the amount of collisions of particles and cross over the energy barrier. Wilbraham and others argue that the main work of increasing the temperature is to increase the number of particles that have copious kinetic energy to react when they collide. More colliding breakwaterecules are energetic enough to slip over the energy barrier to become products. The frequency of high energy collisions between reactants increase, thus, products form faster.The illustration above shows the basis for the postulate reproduction the temperature increases the rate of reaction because the added kinetic energy allows a larger fraction of reactants to go over the hill, (Norton, 2003).C. Risk AssessmentSulphuric acid is a strong, corrosive substance. Therefore, care should be observed when performing the experiment. I will keep in mind the following honestty precautions to en sure a safe experimentTo protect the eyes from the strong acid, goggles should be worn.Care in handling the sulphuric acid should be observed. I will not pipette acid by mouth.The temperature of the water baths should be ascertained cautiously to prevent scalding. The beaker with hot water bath should be set up carefully to prevent it from cosmos knocked over.D. Fair testTo ensure a fair test and high reliability of results from this experiment, I will observe the following peaks solely apparatus and equipment shall be cleaned after each time where the time it takes to collect 100 cc of hydrogen foul up is obtained at each run of the experiment.The read for the volume of the sulphuric acid shall be made very carefully by reading from the lower meniscus of the 100 cubic centimeter mark.The volume of the sulphuric acid and the system of weights of the magnesium ribbon will be measured very accurately for all time measurements at every temperature direct at each run of the experi ment.The bung should be correctly and tightly placed to prevent the collected hydrogen gas from escaping.In order to carry through a constant and stable temperature for each time measurement, after adding the magnesium ribbon to the sulphuric acid, I will wait for 20 seconds to make sure that the temperature is kept constant. .Procedure of the experimentMaterials neededFor this experiment, the following are the materials that are to be used0.4 grams of Magnesium ribbon100 cubic centimeters of 0.3 Molar sulphuric acid100 cc gas syringe for the collection of the hydrogen gas (H2)stopwatch for measuring the time it takes to collect 100 cubic centimeters of the H2 gasThermometer for measuring the temperature of the hot water baths200 cc conical flask for the sulphuric acid500 ml graduated cylinder for measuring the sulphuric acid500 ml beaker for the water bathswater baths with the following temperatures 18.5C, 30C, 40C, 50C, 60C, and 70C.analytical balance for measuring 0.4 grams of m agnesium ribbonProcedure1. Set up the materials while making sure that they are clean and the reagents are not contaminated.2. Using a graduated cylinder, measure 100 cc of 0.3 seawallar concentration of sulphuric acid.3. Carefully weigh 0.4 grams of Magnesium ribbon using an analytical balance to make sure that the weight measurement is accurate.4. Pour the water bath with the desired temperature into the beaker.5. Carefully put the conical flask with the sulphuric acid and into the beaker with the water bath.6. Put the 0.4 grams of magnesium ribbon into the conical flask.7. Measure the time it takes to collect 100 cubic centimeters of hydrogen gas into the gas syringe.8. Repeat steps 1-7 for every desired temperature.10. Label the time recorded as run 1.11. Make 2 more runs for this experiment.IV. ResultsData Gathered The time measurements for each temperature of 18.5C, 30C, 40C, 50C, 60C, and 70C were obtained and tabulated below ( panel 1).Table 1. Temperature Measurements for the Three comports or TrialsThe rates of reaction were obtained using the following formula belowReaction Rate = Volume of gas collected in cc / cartridge clip it takes to collect the gas in secondsThe calculated reaction rates (Volume / Time) for each set temperature for the three runs were tabulated belowTable 2. Reaction Rate of Each RunThe tabulated data of reaction rates above were then graphed for all the three runs. The graph shows the same pattern for all the runs.Graph 1 Reaction Rate Vs. Time Graph of the Three RunsUsing the same data, the average of all calculated reaction rates for each set temperature in every run were taken and tabulated belowTable 3 Average Reaction Rate for Each runThe average reaction rate of all the three runs are then graphed belowGraph 2 Average Reaction Rate Vs. Temperature.Determination of the Activation EnergyThe unidimensional relationship between a rate constant or reaction rate and temperature is given in the equation In k = -Ea/R X 1/T + In A, which is obtained from the Arrhenius equation that relates temperature, rate constant and activation energy. To solve this equation, the rate constant or reaction rate at some(prenominal) temperature values obtained in the experiment are required. Activation energy can be calculated from the obtained temperature values and each respective rate constant by graphing In k versus 1/T. The In k values were obtained using a calculator, where for every value of reaction rate (k) entered into the calculator, the In function is press and the In k value was given. .Table 4 In K and 1 /T Values with the Corresponding Time and Rate of the First RunAfter obtaining the In k and 1 / T values for the first run, they were graphed as shown belowGraph 3 In k versus 1/T (First Run)The side of the In k versus 1/T graph for the first run was obtained the using a line of best barrack through the points in the graph. A perpendicular line was drawn at points A and B. In the graph, A is equal to t he distance between 0.6700 and 0.400 in the Y-axis and B is the distance between points 0.0033 and 0.0032 in the X-axis. So, to solve for the slopeLine A = 0.6740-0.400 = 0.2740 and for line B = 0.0033-.00032= -0.0001Slope = Line A / Line B = 0.02740 / 0.0001 = -2740Graph 4 In k Versus 1/T showing the SlopeThe relationship between slope and activation energy is slope = -Ea/R. Hence, the activation energy for the reaction for the first run is -2740= -Ea/R Ea = (-2740) (8.314J/mol) Ea= 22780.36 J/molSimilarly, data for the second run were obtained and tabulated as shown belowTable 4 In K and 1 /T Values with the Corresponding Time and Rate of the Second RunThe values of In k and 1/T for the second run were graphed as shown belowGraph 5 In k 1/T Graph for the Second RunThe slope of the above In k versus 1/T graph for the second run was determined by drawing a perpendicular line in the best fit points such as in the graph of the first run. For the second run, the slope is equal to -10 93.16So, the activation energy for the second run is -1093.16 = -Ea/R -Ea = (-1093.16) (8.314 J/mol) Ea = 9088.53 J/molData for the In k versus 1/T graph for the third run are as follows were similarly obtained and tabulated as followsThe graph of the tabulated data above is shown belowThe slope of the above In k versus 1/T above is -1274.70So the activation energy for the third run is -1267.89 = -Ea/R -Ea = (1267.89) (8.314 J/mol)Ea= 10541.23 J /molThus, the activation energy values for each run are the followingFirst run 22780.36 J/molSecond run 9088.53 J/molThird run 10541.23 J /molV. AnalysisThe data gathered clearly show that at higher temperatures, the rates of reactions increase up to a certain point, and then continue to slow down. This can be seen in the first 2 graphs, namely Graph 1 Reaction Rate Vs. Time Graph of the Three Runs and Graph 2 Average Reaction Rate Vs. Temperature. This means that after sometime, the rate of reaction slows down because the products are al ready being formed. In the experiment, the plateaus in the graph correspond to the time that the hydrogen gas (H2) are already being formed.The data also showed only one activation energy value for each run. Thus, it only shows that the activation energy in NOT temperature- dependent, NOR is there a direct relationship between the two, since its value does not change with changes in temperature. The relationship between temperature and activation energy as can be concluded in this experiment, is that the temperature increases the capacity of the system to overcome the activation energy needed to form the products. So, the higher the temperature, the faster are the rates or speed of reactions.VI. EvaluationA. Experimental UncertaintyIn the measurement of the varied temperatures for the water baths, the following percentage errors were obtainedFor the reading of 18.5 C, the percentage error is irrefutable or minus 0.5 / 18.5 x 100 = 2.7%For 30 C, the percentage error is Plus or minu s 0.5 / 30 x 100 = 0.16%For 40 C, the percentage error is Plus or minus 0.5 / 40 x 100 = 0. cxxv%For 53 C, the percentage error is Plus or minus 0.5 / 53 x 100 = 0. 94%For 60 C, the percentage error is Plus or minus 0.5 / 60 x 100 = 0. 83%For 70 C, the percentage error is Plus or minus 0.5 / 60 x 100 = 0. 71%In the use of a graduated cylinder with 1 cm scale, the percentage error is plus or minus 0.5 in every 10 cm scale. So, in this experiment, the percentage error can be calculated as0.50/100 X 100 = 0.5%.Experimental OutcomesThe outcomes of the experiment exactly fit my hypothesis or prediction, that as the temperature rises, the faster is the rate of reaction.However, I did not predict the outcome that the activation energy itself is NOT temperature dependent, since it does not change with the changes in temperature. This is shown in the experiment results, where there was only one activation energy value for all temperature measurements in each run of the experiment. The relati onship between temperature and activation energy is based on the fact that the temperature increases the capacity of the system to overcome the activation energy needed to form the products.Design of the ExperimentI deal that to improve the experiment, I may need to compare the reaction used inthis experiment to a reaction that uses a catalyst to investigate the effect of catalysts on the activation energy and speed of reactions.ReferencesActivation Energy, 2006. http//chemed.chem.purdue.edu/genchem/topicreview/bp/ch22/activate.htmlactAccessed February 28, 2006.Collins, M. (1999), Activation Energy and the Arrhenius Equation. Abbey Newsletter, Vol.23, Number 3, 1999. http//palimpsest.stanford.edu/byorg/abbey/an/an23/an23-3/an23-308.html. Accessed February 29, 2006.Energex, 2006. Kinetic Theory. http//www.energex.com/au/switched_on/project_info/electricity_production_glossary.htmlK. Accessed February 29, 2006.Norton, 2003. Key Equations and Concepts .Chemistry in the Science Context . http//www.wwnorton.com/ alchemy/concepts/chapter14/ch14_5.htm Accessed February 27, 2006.The Shodon Education Foundation, Inc. 1998. The Arrhenius Equation. http//www.shodor.org/UnChem/advanced/kin/arrhenius.html. Accessed February 27, 2006.Wikipedia, 2006. Collision Theory. http//en.wikipedia.org/wiki/collision_theory. Accessed February 27, 2006.Wilbraham, A. Stanley D., Matta, M., 1997. Chemistry. 4th edition. Menlo Park, California Addison-Wesley. (pp.490-494)..