Chemistry energy and how can it be determined

        Chemistry IA Name : Pranay SamineniTitle : The relationship between the temperature and the rate of reaction in a chemical reaction.Introduction : Last academic year, towards the end, in IB chemistry hl class, my class had the chance to learn about the concentration, temperature, catalysts, etc and their effects on the rate of reaction in a chemical reaction. I knew that the rate of reaction had a relationship with the factors but I wanted to know how it changes witness it for myself. I wanted to perform an experiment for myself to see what it actually is like. This IA is potentially an opportunity for me to test my understanding on the topic and Research Question :What is the activation energy and how can it be determined through the relationship between the temperature and the rate of a said reaction?Background Information : Rate of reaction in its most basic definition is the speed at which the reaction takes place. The rate of reaction can be calculated by using Rate of Reaction = Molestime of reactionCollision Theory : In order for atoms/molecules/ions to react, they must collide with each other, the rate of reaction is directly proportional to the collision frequency. The greater the number of collisions, the faster the reaction will take place. Activation Energy : For these collisions to take place and the reactions to happen, a minimum amount of kinetic energy must be possessed by the particles that are going to collide with each other. This minimum amount of energy required to initiate a reaction is called activation energy.In 1889, Arrhenius found that the plotted graph of the natural log of the rate constant and the reciprocal of the temperature produced a straight line. He identified the slope of this graph to be related to the energy term m=-EaRwhere E is the activation energy and R is the ideal gas constant. This formula will help us determine the activation energy by examining the relationship between the temperature and the rate of reaction of a solution.Kinetic Molecular Theory – This theory states that the temperature is a measure of average kinetic energy of particles.Rate Constant – The rate constant can be found using the formula rate =kAB. Where k is the rate constant and A and B are the concentrations of the solutions.The relationship between temperature and rate of reaction : Increasing the temperature of a solution results in increasing the kinetic energy of the particles present in the solution. This is at a molecular level and an increase in the kinetic energy would result in the particles moving faster hence leading to more collisions between each other and since collisions are directly proportional to the rate of reaction, increasing the temperature will increase the rate of reaction. This explanation will further help us develop the hypothesisBy calculating the rate constant for the equation, with the use of Arrhenius equation, the activation energy will be derivedHypothesis : As there is a rise in the temperature of the reactions, the rate of reaction will increase, leading to a larger rate constant hence leading to a larger slope which will give a greater activation energy.Variables :The independent variable in this case is the Temperature of HCl which is being changed. The HCl solution is either heated or cooled down depending on the trial. This is the method used to change the Independent Variable. It is measured using a Thermometer. The Dependent variable in this case is the time taken or rate of reaction. The rate of reaction is basically, 1/T where T is the time period or the time until the X mark disappears in this case. A stopwatch is used to record the time it takes for the solutions to react. The time measured can be taken up to 1 decimal place, i.e. 3 significant figures. Materials RequiredHydrochloric Acid – 2MMagnesium ribbonErlenmeyer FlaskGraduated CylinderBunsen BurnerRetort StandRing ClampThermometerStopwatchSandpaperMass BalanceProcedure : Step 1 –  Make 50 cm3 of HCl using 2 M of 16 cm of HCl and add 34 cm of water to it.Step 2 – Pour the 50 cm of HCl into the Erlenmeyer flaskStep 3 – Measure 0.2 g of Magnesium strips. Make sure to clean the magnesium with sandpaper before weighing it to remove all the impuritiesStep 4 – Set up retort stand with bunsen burner and ring clampStep 5 – Heat the HCl in the flask to 70 degrees with the thermometer inside the solutionStep 6 – Drop the 0.2 g of measured Magnesium into the flaskStep 7 – Start recording the time of the reaction with a stopwatchStep 8 – Perform steps 1 through to 8 three trialsStep 9 – Perform steps 1- 8 with the temperature of HCl being 40 degrees and 10 degrees keeping the amount of Mg constantRaw DataTable 1 : Temperature of HCl at 70o Celsius (±0.5oC)TrialMass of Mg(±0.01g)Time of Reaction(±0.5s)10.20030.020.19829.430.19730.5       Table 2 : Temperature of HCl at 55o Celsius (±0.5oC)Trial #Mass of Mg(±0.01g)Time of Reaction(±0.5s)10.233.620.19733.330.20134.2 Table 3 : Temperature of HCl at 40o Celsius (±0.5oC)Trial #Mass of Mg(±0.01g)Time of Reaction(±0.5s)10.19937.220.20436.530.19837.8 Table 4 : Temperature of HCl at 25o Celsius (±0.5oC)Trial #Mass of Mg(±0.01g)Time of Reaction(±0.5s)10.20542.420.19939.930.19841.0   Table 5 : Temperature of HCl at 10o Celsius (±0.5oC)Trial #Mass of Mg(±0.01g)Time of Reaction(±0.5s)10.19945.820.19844.530.19945.1 Qualitative Observations.The color of the Hydrochloric Acid was transparent. As the temperature increased, the HCl started bubbling. The Magnesium ribbon was black until I used the sandpaper to clean it up to give it a shiny silver color. When the ribbon was dropped into the HCl, tiny white bubbles covered the ribbon making the reaction seen to naked eye. The bubbling also made a crisp sound when dropped. Each of the trials in the quantitative data have been taken thrice to achieve higher precision in the final results.Processed DataFinding the average mass and average time of reactionSample Calculation – Average mass = mass in trial 1 + mass in trail 2 + mass in trial 330.199 + 0.198 + 0.1993=0.198Table 6Temperature of HCl (±0.5oC)Average Mass of Mg (±0.01g)Average time of reaction (±0.5s)700.19829.9550.233.7400.20037.1250.19941.1100.19845.1Finding the rate of reaction :Moles = MassMolar MassSample Calculations0.224.305=0.00823Rate of reaction =Moles time of reaction0.0082337.1=2.21 10-4moles/sUncertainty for the the moles can be found by converting the uncertainty on the mass of Mg to percentage and adding the uncertainty percentage from the time of reaction and converting the percentage back into moles/s. This is because the uncertainty on the molar mass is negligible. Sample Calculation0.010.2100 =5%0.0129.9100 =0.03%=5.03% uncertainty in the rate of reaction.Table 7Temperature of HCl(±0.5oC)Average Mass of Mg(±0.01g)Average time of reaction(±0.01s)Rate of Reaction (mol/s)Uncertainty in rate of reaction 700.19829.90.000272460.00001385550.233.70.0002440.00001228400.237.10.000221800.00001115250.19941.10.0001990.00001006100.19845.10.000180630.00000916Graph 1The gradient of the graph is 1.51310-6From this we can find the Rate constant using the formula  rate =kABwhere A is the concentration of HCl and B is the concentration of Mg. However, since Mg is a solid, we take its concentration to be 1 because it doesn’t affect the reactant amount atthe equilibrium in the reaction.Finding the concentration of HCL – m1v1=m2v2Where m1 is the initial concentration and m2 is the final concentration and v1 is the initial volume and v2 is the final volume.216=m2503250=m2m2=0.64Sample Calculation -0.00001385=k0.641k=2.1610-5Temperature (Celsius)Rate Constants 700.0000216550.0000191400.0000174250.0000157100.0000143Graphing the natural log of the rate constant and the reciprocal of the temperatureReciprocal of Temperature (Celsius)Natural log of rate constant0.0143-10.740.02-10.860.025-10.950.04-11.060.1-11.15Graph 2The slope of the graph is -3.930.From this, we can find the activation energy by using the formula m=-EaRwhere m is the slope of the graph above. By rearranging the equation, we get mR=-Ea-3.9308.314 =-EaEa=32.6 KJ/molThe activation energy determined from the relationship between temperature and the rate of reaction is 32.6 KJ/mol.ConclusionThe relationship between temperature and rate of reaction can be explained through the use of Collision Theory and Kinetic Molecular Theory.As seen from Graph 1, there is a positive linear relationship between the temperature and the rate of said reaction. This helped us establish the relationship which led to the rate constants for each of the temperatures. These rate constants were then taken in their natural log form and graphed with the reciprocal of temperature. There was a negative linear correlation as seen from graph 2. The slope of this graph which turned out to be -3.930 was then used to determine the activation energy for the reaction. The activation energy for the reaction came out to be 32.6 KJ/mol. To find the validity of the experiment and the acquired value, we need to compare it with the literature value of the said experiment. The literature value of the reaction is 33.8KJ/mol. 33.8-32.633.8x 100 = 3.55%.This percentile is rather small but still considerably big that may give us an insight as to how to improve the experiment. Therefore, suggesting that the experiment has been successful in proving the relationship between Temperature and rate of reaction. EvaluationOne of the factors that could’ve affected the accuracy of the experiment is that for each trial, the HCl solutions were diluted individually. This allows for a higher rate of error as a fixed error is associated with the beaker used. This can been avoided by using a larger beaker with larger amounts of HCl before the experiment began.Another one of the factors that could’ve affected the accuracy of the experiment is the room temperature and its fluctuations. This could’ve tampered with the temperature of the HCl. To overcome this problem, the experiment can been conducted in a closed room with a stable room temperature.Another factor that might’ve affected the speed of the reaction is the exposure to light. The experiment was performed in a classroom with lights and windows. Therefore, the light could’ve increased the energy of the particles in the reaction to speed the process up. This problem can be avoided by performing the experiment in a closed room.Another factor that might’ve affected the speed is the cleaning of the magnesium ribbon. As I had noticed from experience, the ribbon doesn’t react with the hydrogen unless it’s cleaned well. If all the pieces of ribbon hadn’t been cleaned well, the precision of the experiment is compromised. This can be avoided by making sure the magnesium ribbon are cleaned before the reaction.Control VariablesThe Control VariableHow it affects the experimentHow to keep it controlledConcentration of the Hydrochloric AcidChanging the concentration of HCl will have the same effect as changing the concentration of Magnesium and hence is not desiredDo not use different concentrations of HCl for different trialsCatalystCatalysts increase the rate of reaction by not chemically changing  themselves to essentially bring the reacting particles closer to each other increasing the rate of reactionSince there is no catalyst, as long as the reagent isn’t changed, the experiment can go smoothly.Temperature of the surroundingsThe temperature of the surroundings in many cases affects the reaction rate leading to false resultsIf most of the experiment could be performed in standard conditions, and if possible being done inside the fume cupboard would lead to better results.Assessment of Safety, Ethical and environmental issuesHazardLevel of Risk and RepercussionsPreventionMagnesiumLow, irritant(not in solid form)Avoid contact with eyes and ingestionHydrochloric AcidLow, irritantAvoid contact with eyes, ingestion and inhalation. Usually is a pretty strong acid but since the concentration is low, it doesn’t have any major effects.There are no ethical and environmental threats caused from the experiment ReferencesN.p., 2017. Web. 10 Sept. 2017.”Classic Chemistry Experiments : The Effect Of Temperature On Reaction Rate- Learn Chemistry.” N.p., 2017. Web. 10 Sept. 2017.”Temperature – Chemistry Encyclopedia – Reaction, Water, Metal, Gas, Number, Equation, Property, Mass.” N.p., 2017. Web. 10 Sept. 2017.”The Effect Of Temperature On Rates Of Reaction.” N.p., 2017. Web. 10 Sept. 2017.        “6.2 Factors Affecting The Rate Of Reaction”. IB CHEM NINJA. Web. 6 Apr. 2017.        “Reaction Rate”. Chemistry Libre Texts. Web. 6 Apr. 2017.        “Student Safety Sheets”. Cleapss. N.p., 2013. Web. 6 Apr. 2017        “13.4.” N.p., 2017. Web. 22 Oct. 2017.”Orders Of Reaction And Rate Equations.” N.p., 2017. Web. 22 Oct. 2017.”Rate Constants And The Arrhenius Equation.” N.p., 2017. Web. 22 Oct. 2017.”Rate Of Reaction Of Hcl & Mg Lab Answers.” SchoolWorkHelper. N.p., 2017. Web. 22 Oct. 2017.


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