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Potassium permangonate

Extracts from this document...

Introduction

An Investigation into the Kinetics of the reaction between Potassium Permanganate and Oxalic Acid with a Sulphuric Acid Catalyst Aim The primary objective of my investigation is determining the orders of reaction for the oxidation of oxalic acid by potassium permanganate, with a sulphuric acid catalyst: 2 MnO4-(aq ) + 5 H2C2O4(aq ) + 6 H3O+(aq ) --> 2Mn2+(aq ) + 10 CO2(aq ) + 14 H2O I will find this by applying alterations to certain factors that affect the rate of the reaction, and observing which ones have a greater bearing. These factors will be the concentrations of each reactant and the catalyst, and also the temperature of the solutions at the time of reaction. I will consider: o What is the rate equation? o What is the order of reaction for each reactant? o What is the activation enthalpy of the reaction? Apparatus * 250 cm� volumetric flasks * Bulb pipettes-10cm�, 25cm�, 50cm �� * Teat pipettes * 100 cm� beakers * Distilled water * Digital Thermometer * Water Bath * Colorimeter * Stopclock * Cuvettes Apparatus Descriptions and Justifications The 250 cm� volumetric flasks have been designed to allow the preparation of solutions, with a very high degree of accuracy regarding both volume and concentration. I will be using class B flasks, which have a tiny error. These volumetric flasks have been calibrated at room temperature, so will be suitable for my investigation as this will be the temperature at which my solutions will be prepared, so my concentrations will be as accurate as possible. The bulb pipettes I am going to use will be necessary for measuring and transferring solutions, both for creating new concentrations of solutions and the injection of solutions into the reaction itself. As with the volumetric flasks, the pipettes will be extremely accurate, of class B, giving a very small error. The teat pipettes I plan to use are effective tools in quickly transferring small amounts of solution up to 5cm�. ...read more.

Middle

As the colour of the solution I shall be observing is a vivid violet, I shall set the colorimeter to the complimentary filter green/yellow. I will then proceed to reset the colorimeter with distilled water (absorbance 0), and place samples of each concentration of potassium permanganate in the colorimeter one by one, measuring the absorbance of each. I shall then plot a graph of absorbance against concentration, and use this as a calibration graph. The next stage will be preparing the rest of my solutions. To make my solutions, I will place a particular amount of potassium permanganate in volumetric flask using a bulb pipette, filling the rest with distilled water until the meniscus reaches the thin line on the neck of the flask, diluting the solution in order to produce different concentrations. The amount of potassium permanganate used will depend on the concentration I intend to produce. To find this concentration, I will use the following formula: New concentration = old concentration x volume of solution to be diluted volume of water + solution As I am looking at how changing different factors in the reaction can affect the reaction rate, I will also make various concentrations of the oxalic acid and sulphuric acid, using the same method. The strongest sulphuric acid I will use is 2 moldm ��, so will produce the following concentrations of sulphuric acid: * 1 moldm �� * 0.5 moldm �� * 0.25 moldm �� * 0.125 moldm �� * 0.1 moldm �� The concentrations of oxalic acid I will use are: * 0.25 moldm �� * 0.025 moldm �� * 0.0025 moldm �� * 0.00025 moldm �� * 0.000025 moldm �� The concentrations of Potassium permanganate used will be: * 0.01 moldm �� * 0.005 moldm �� * 0.001 moldm �� * 0.0005 moldm �� * 0.0001 moldm �� These concentrations were carefully selected after I carried out a set of trial runs, including experiments with many different concentrations of each of the solutions. ...read more.

Conclusion

After time in the sunlight, during use, the solutions of potassium permanganate may have been partially oxidised, reducing the actual concentration of the chemical. Due to a faulty motion sensor that controlled the lights within the room, the intensity of light was not constant. If given the opportunity to change my investigation I would do so through the employment of the following things: * Calculating the method of producing solutions with the least tolerances in order to reduce inaccuracies further down the line. * Using class A containers, again to reduce inaccuracies in my solutions. * Doing a greater number of experiments, using more concentrations and temperatures over a greater range to find results that are more representative of the reaction I am observing. * Ensuring my permanganate solutions were always stored in the dark * Create an environment in which the temperature and light levels were constant, so I new that there was only one variable and could confirm the changes in result were due to the changes I have made to the reactants or system, as opposed to something external. * Use a more reliable colorimeter as to reduce the likelihood of incorrect readings. It is also true that any mistakes or inaccuracies in my results may have been caused by qualitative errors, for instance, my judgment when producing solutions, or my reactions when taking recordings at certain times, which is particularly significant for the faster reactions. These errors can be reduced through care and effort, but as a human it is inevitable that these mistakes will be made to a certain extent. The unknown error of the original solutions is another cause of inaccuracies that could not be helped. Regardless of any errors and mistakes made, I believe the majority of my results and analysis serve as support of the validity and general reliability of my finding. Although my investigation my suffer inaccuracies in specific aspects of its design and results, the conclusion drawn from it can be regarded as valid and justifiable. ?? ?? ?? ?? ...read more.

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