The Harcourt Essen Experiment
The aim of this investigation is to: 1) find the rate equation for the reaction between hydrogen peroxide, potassium iodide and sulphuric acid by using the iodine stop clock method and plotting graphs of 1/time against concentration for each variable. Then to find the activation energy by carrying out the experiment at different temperatures using constant amounts of each reactant and then by plotting a graph of in 1/t against I/T, 3) to deduce as much information about the mechanism as possible from the rate equation.
The first experiments investigate the order of reaction with respect to the reactants; hydrogen peroxide, potassium iodide and sulphuric acid by varying the concentrations and plotting them against 1/time. An initial rate technique is used in this experiment so ‘the rate of reaction is inversely proportional to time.’ To find the order of reaction in respect to the reactants, 1/time is plotted against the concentration of Hydrogen Peroxide using the equation:
1/t = k(a) ͯ
t = time, a = volume of reactant, k is a constant of proportionality; x is the order of reaction. Because k is a constant of proportionality 1/t is directly proportional to the rate of reactant. Then to find out the order of reaction in a catalysed system the volume of ammonia molbydate is varied and the concentration of the other reactants kept the same. Thirdly to investigate the activation energies, the concentrations are kept the same and the temperature is varied.
Background information:
The Harcourt Essen experiment consists of two reactions:
2H+ (aq) + H202(aq) + 2I-(aq) 2H2O(l) + I2(aq)
This is the first reaction in the Harcourt Essen experiment. The iodine is oxidised to produce I2 wh...
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... point was subjective; however it would have been a systematic error because I consistently judged the end point of my experiment. To eliminate this inaccuracy I should have used a colorimeter to judge the end point of my experiment.
Also the stop clock had a degree of percentage error measured by:
There was also a percentage error with the graduated pipettes calculated by:
The percentage error of the burette:
The percentage error of the graduated pipettes:
Overall percentage error:
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
There were no significant error factors that may have affected the arrangement of the lab experiment. Everything went smoothly with relative ease.
In this experiment, there were several objectives. First, this lab was designed to determine the difference, if any, between the densities of Coke and Diet Coke. It was designed to evaluate the accuracy and precision of several lab equipment measurements. This lab was also designed to be an introduction to the LabQuest Data and the Logger Pro data analysis database. Random, systematic, and gross errors are errors made during experiments that can have significant effects to the results. Random errors do not really have a specific cause, but still causes a few of the measurements to either be a little high or a little low. Systematic errors occur when there are limitations or mistakes on lab equipment or lab procedures. These kinds of errors cause measurements to be either be always high or always low. The last kind of error is gross errors. Gross errors occur when machines or equipment fail completely. However, gross errors usually occur due to a personal mistake. For this experiment, the number of significant figures is very important and depends on the equipment being used. When using the volumetric pipette and burette, the measurements are rounded to the hundredth place while in a graduated cylinder, it is rounded to the tenth place.
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
Chemical kinetics is the study of rates of chemical processes with respect to reaction rates, result of differing variables, re-arrangement of atoms, formation and intermediates etc (Theodore L. Brown,2010)(Chung Chieh,2016). The study of chemical kinetics is one that is a major importance in chemical research. It is powerful research tool in determining the reaction mechanism of several different reactions in chemistry(The University of Sydney,2002).
...ore reliable if it were possible to do more trials to make sure that the data that was found was correct. This experiment could’ve been more reliable if some mistakes weren’t made like, the inaccuracy of weighing and measuring the potatoes. This could have affected the results by throwing off all the data and giving numbers that were nowhere near accurate. Another mistake that could’ve been made was the amount of solution put into each test tube. Some of the test tubes may have had to little or not enough of its solution. Some ways to fix both of these problems would be to weigh and measure each potato core more than once which is not what was done. A way to fix the inaccuracy of the amount of salt water put into each test tube would be to measure the solutions into a different container to make sure it’s an accurate measurement, then pouring it into the test tube.
While measuring the effect of the use of a catalyst and temperature on the reaction rate, several factors must be kept constant. During the reaction with a catalyst, the temperature will be kept constant (at room temperature), concentration, pressure and since the reaction involves liquids, the surface area will be kept constant at all times, however they must be mixed the same.
Before conducting my experiment I will research into, amongst other things, the factors that affect the rate of a reaction. This is so that I may enough information to understand the effect of temperature on the rate of a reaction and also gain appropriate understanding to make a suitable prediction as to what the outcome of my experiment will be.
The time taken for this to happen is the measure of the rate of reaction. We must do this several times, and change the concentration of sodium thiosulphate. The rate of reaction is a measure of the change, which happens during a reaction in a single unit of time. The things that affect the rate of reaction are as follows. Surface area of the reactants Concentration of the reactants
In this lab experiment, around 5 grams of hydrogen peroxide went through a chemical reaction with potassium iodide, producing oxygen gas and water vapor. After three trials of the experiment concluded, Dalton’s law of partial pressure and the ideal gas law was used to determine the number of moles of oxygen produced and the percent hydrogen peroxide in an aqueous solution. The average number of moles of oxygen produced within the experiment was 0.002537 mol. O2 and the average mass percent of hydrogen peroxide was calculated as 3.434%. The mass percent of hydrogen peroxide was slightly over the accepted amount of 3%, indicating that some tiny errors had occurred during the experiment.
The rate law for this iodine clock reaction is rate=k[I-][S2O82-]. The rate law could not have been predicted using the coefficients in the balanced chemical
Chemical kinetics is the study and examination of chemical reactions regarding re-arrangement of atoms, reaction rates, effect of various variables, and more. Chemical reaction rates, are the rates of change in amounts or concentrations of either products or reactants. Concentration of solutions, surface area, catalysts, temperature and the nature of reactants are all factors that can influence a rate of reaction. Increasing the concentration of a solution allows the rate of reaction to increase because highly concentrated solutions have more molecules and as a result the molecules collide faster. Surface area also affects a
One vital process in the human body observed in chemistry is the idea of chemical kinetics. Chemical kinetics is the study of the rate of reactions, or how fast reactions occur.1 Three factors that affect chemical kinetics are concentration, temperature, and catalysis. As the concentration of a substance increases, the rate of the reaction also increases.1 This relationship is valid because when more of a substance is added in a reaction, it increases the likelihood that the
The point of this lab is to learn about systematic errors, which occurs when a mistake happens when setting up an experiment. When a systematic error occurs the accuracy of the experiment is thrown off. The point of the experiment was to figure out the relationship between precision and accuracy.
The aim is to find out how does the rate of reaction between sodium thiosulphate