Factors Affecting the Amount of Carbon Dioxide given off when a Carbonate reacts with an acid Essays

Factors Affecting the Amount of Carbon Dioxide given off when a Carbonate reacts with an acid Essays Factors Affecting the Amount of Carbon Dioxide given off when a Carbonate reacts with an acid Essay Factors Affecting the Amount of Carbon Dioxide given off when a Carbonate reacts with an acid Essay When an acid reacts with a metal carbonate, a metal salt, water and carbon dioxide are produced. The amount of carbon dioxide produced depends on various factors. The aim of this experiment is to find out how much Carbon Dioxide (CO2) is given off when different masses of Calcium Carbonate (CaCO3) are reacted with Hydrochloric acid (HCl). The factors affecting the amount of CO2 produced are listed below. Variables Continuos Variables Variable Temperature Very hard to keep constant. Amount of acid As long as there is excess for all carbonate to react, it is therefore not relevant. Concentration of acid Any acid as long as there are enough H+ ions in the acid to react with carbonate. Pressure Hard to keep constant. Surface area Hard to measure surface area of powdered Calcium Carbonate. Rate of stirring Hard to keep constant and very inaccurate. Time Not relevant as rate of reaction has no effect on amount of Carbon Dioxide produced. Amount of carbonate This is the factor under investigation Discontinuous Variables Factor Type of acid All acids contain H+ ions required for reaction. Type of carbonate Some carbonates such as Sodium are soluble, therefore I will not be able to investigate. In my investigation I have chosen to investigate the amount of carbonate rather than the type of carbonate as amount is a continuos variable and will produce a pattern rather than a random collection of carbonates. Constants The following variables will be kept constant: Variable Control of variable Temperature Room Temperature Type Concentration of acid 2M Hydrochloric Acid Amount of Acid 50ml Pressure Atmospheric Type of carbonate Calcium Carbonate Rate of stirring None Fair Test In order to make this investigation as fair as possible, all the constant variables must remain constant throughout the experiment, as mass of carbonate is the only variable changing. The experiment must be repeated at least twice so as not to get any anomalous results. The constants must be checked every time a result is taken. Prediction The volume of Carbon Dioxide produced will increase directly proportionally with the mass of Calcium Carbonate used. Calcium Carbonate Hydrochloric Acid Calcium Chloride Water Carbon Dioxide CaCO3 HCl CaCl2 H2O CO2 1 2 1 1 1 100g 73g 111g 18g 24dm3 g of CaCO3 produces 24000cm3 of CO2 g of CaCO3 produces 48000cm3 of CO2 g of CaCO3 produces 72000cm3 of CO2 g of CaCO3 produces 96000cm3 of CO2 From these calculations it is visible to say that doubling the mass of carbonate doubles the volume of Carbon Dioxide produced. Tripling the mass of carbonate triples the volume of Carbon Dioxide produced. The relationship is directly proportional and the graph of mass against volume shows a straight line through the origin. Safety Acids are corrosive and an irritant. Safety glasses and labcoats must be worn at all times. Wash hands after experiment. Reacting Moles Masses Calcium Carbonate Hydrochloric Acid Calcium Chloride Water Carbon Dioxide CaCO3 HCl CaCl2 H2O CO2 1 2 1 1 1 100g 73g 111g 18g 24dm3 g of CaCO3 produces 24dm3 of CO2 as 1 mole of any gas at room temperature and pressure occupies 24dm3. g of CaCO3 produces 240cm3 of CO2 g of CaCO3 produces 192cm3 of CO2 g of CaCO3 produces 144cm3 of CO2 g of CaCO3 produces 96cm3 of CO2 g of CaCO3 produces 48cm3 of CO2 The relationship is directly proportional and the graph of mass against volume shows a straight line through the origin. I have chosen to investigate the masses shown above ranging from 0.2g to 1.0g. This should give me a wide and consistent spread of results. I have decided to collect the CO2 produced in measuring cylinders, which the maximum size is 250ml. I will have to use masses to fit the size of the measuring cylinder. My calculations above confirm that none of the masses will produce more than the amount of the measuring cylinder. Sample Results table Mass of Calcium Carbonate (g) Volume of expected Carbon Dioxide (cm) Actual volume of Carbon Dioxide produced (cm) 0.2 48 0.4 96 0.6 144 0.8 192 1.0 240 Preliminary Work In my preliminary work I investigated the two extremes, 0.2g 1.0g of Calcium Carbonate. Mass of Calcium Carbonate (g) Volume of expected Carbon Dioxide (cm) Actual volume of Carbon Dioxide produced (cm) 0.2 48 34 1.0 240 176 In my preliminary work I realised that the actual volume of Carbon Dioxide was not the same as the expected volume of Carbon Dioxide. The percentage error was about 70%. This is because Carbon Dioxide is slightly soluble in water and some of the gas has dissolved forming Carbonic Acid. I also found several improvements that I could make to my final plan, being: 1. A fair amount of Calcium Carbonate was left un-reacted in the tube: The flask is shaken gently until all the Calcium Carbonate has fully reacted. 2. The delivery tube repeatedly dislodged itself from underneath the measuring cylinder. The delivery tube is held by hand to stop it dislodging. Method Apparatus required: * 50ml measuring cylinder (accurate to 1ml) * 100ml measuring cylinder (accurate to 1ml) * 250ml measuring cylinder (accurate to 2ml) * Trough * Delivery Tube * Round bottomed flask * Calcium Carbonate * 2M Hydrochloric acid * Balance * 5cm Tubes Diagram Method * Set apparatus as in diagram * Place a piece of paper on the balance and tear it * Measure out the required mass of Calcium Carbonate * Pour massed amount of Calcium Carbonate into tube * Place tube in the lip of the round bottomed flask * Connect the delivery tube to the flask * Tap gently so that the tube falls into the acid * Shake fairly vigorously, making sure you are holding the delivery tube so that it doesnt dislodge from under the measuring cylinder. * When all the Calcium Carbonate has reacted record the final volume of gas obtained. Obtaining Evidence Accuracy of apparatus For this experiment the measurements were recorded as accurately as the apparatus allowed: * 50ml measuring cylinder (accurate to 1ml) * 100ml measuring cylinder (accurate to 1ml) * 250ml measuring cylinder (accurate to 2ml) In order to obtain reliable results I repeated the experiment twice. This was done to ensure the all three of the results follow the same trend. To keep this experiment a fair test all three times the following were kept constant: Variable Control of variable Temperature Room Temperature Type ; Concentration of acid 2M Hydrochloric Acid Amount of Acid 50ml Pressure Atmospheric Type of carbonate Calcium Carbonate Rate of stirring None The following results were obtained: Experiment 1 Mass of Calcium Carbonate (g) Volume of expected Carbon Dioxide (cm3) Actual volume of Carbon Dioxide produced (cm3) 0.2 48 36 0.4 96 80 0.6 144 94 0.8 192 158 1.0 240 190 Experiment 2 Mass of Calcium Carbonate (g) Volume of expected Carbon Dioxide (cm3) Actual volume of Carbon Dioxide produced (cm3) 0.2 48 30 0.4 96 68 0.6 144 100 0.8 192 142 1.0 240 192 The results obtained above which are in bold I found to be anomalous results. In Experiment 1 -0.6g In Experiment 2 -1.0g I therefore repeated them: Repeats Mass of Calcium Carbonate (g) Volume of expected Carbon Dioxide (cm3) Actual volume of Carbon Dioxide produced (cm3) 0.6 144 98 1.0 240 188 Analysing From the results obtained I could plot the following graphs: 1) Experiment 1 A graph to show mass of CaCO3 against amount of CO2 produced 2) Experiment 2 A graph to show mass of CaCO3 against amount of CO2 produced 3) A graph to show mass of CaCO3 against average amount of CO2 produced with expected result All three of the graphs show that as mass of Calcium Carbonate is increased the amount of Carbon Dioxide produce increases. The straight line goes through the origin and therefore this relation is directly proportional. For example in experiment 1: 0.2g of CaCO3 produces 36cm3 of CO2 0.4g of CaCO3 produces 80cm3 of CO2 0.4g of CaCO3 produces 80cm3 of CO2 0.8g of CaCO3 produces 158cm3 of CO2 For example in experiment 2: 0.2g of CaCO3 produces 30cm3 of CO2 0.4g of CaCO3 produces 68cm3 of CO2 0.4g of CaCO3 produces 68cm3 of CO2 0.8g of CaCO3 produces 142cm3 of CO2 The examples above are not exactly directly proportional, but are very close. This is because of experimental error. Molar Calculation Calcium Carbonate Hydrochloric Acid Calcium Chloride Water Carbon Dioxide CaCO3 HCl CaCl2 H2O CO2 1 2 1 1 1 100g 73g 111g 18g 24dm3 g of CaCO3 produces 24dm3 of CO2 as 1 mole of any gas at room temperature and pressure occupies 24dm3. g of CaCO3 produces 240cm3 of CO2 g of CaCO3 produces 192cm3 of CO2 g of CaCO3 produces 144cm3 of CO2 g of CaCO3 produces 96cm3 of CO2 g of CaCO3 produces 48cm3 of CO2 From the molar calculations and from graph 3 it is visible that the relationship is directly proportional and the graph of mass against volume shows a straight line through the origin. For example: 0.2g of CaCO3 produces 48cm3 of CO2 0.4g of CaCO3 produces 96cm3 of CO2 0.4g of CaCO3 produces 96cm3 of CO2 0.8g of CaCO3 produces 192cm3 of CO2 After processing my results it can now concluded that as the mass of Calcium Carbonate is increased the amount of Carbon Dioxide produced increases. This relation is directly proportional. This can be supported with both my obtained results and the calculated results. These results do confirm the original prediction made earlier. The results support the original prediction as it was predicted that the volume of Carbon Dioxide produced will increase directly proportionally with the mass of Calcium Carbonate used. The results support the original prediction fairly well but not fully as there is one discrepancy. The results obtained are not exactly directly proportional but are close enough to being so. These slight differences are due to experimental error, which will be explained in detail in the Evaluating section in more detail. Evaluating Considering the equipment provided I think that the results obtained were fairly consistent and reliable. The results gave a distinct pattern similar to that of the expected results. I would consider the evidence to be reliable as they both follow the same trend on the graph. The experiment was repeated twice although in both experiments I obtained anomalous results. Both values are distinctly distanced from the line on the graph. On obtaining the anomalous results I repeated both the values and I found that both results were fairly similar to those previously obtained and therefore they seemed to be anomalous but they proved not to be as all three results fell all close to each other. I would consider the experiment not to be as reliable, as there were several factors, which need criticism: * The purity of the CaCO3 For this experiment the purity of the calcium carbonate was 98% and if it had been 100% pure than I think it would have made a difference. * Temperature of the room fluctuated. The temperature did remain constant throughout the whole experiment and so it might have had an effect on the experiment. * Not all the CO2 produced was collected. This is because Carbon Dioxide is slightly soluble in water and some of the gas has dissolved forming Carbonic Acid. Gas was still being left in the delivery tube. * Bubbles of gas were stuck to the measuring cylinder when reading was taken. When the final amount of gas produced was recorded, a fair amount of gas bubbles were on the sides of the measuring cylinder and therefore the volume will not be correct. * The flask is shaken fairly vigorously. In my method I had said that to dissolve all the CaCO3 I would need to shake the flask fairly vigorously. This however was not the case. The more vigorously the flask is shaken the more CO2 will dissolve and therefore only gentle shaking was needed. The conclusion obtained is supported fully by the results obtained. I consider my range of results to be an appropriate range in which I have made the conclusion. My values spread from 0.0g 1.0g, giving a wide spread. However this conclusion is only for the results obtained, this may not be the case if the experiment is done for values outside the range I investigated. If I were to do this experiment again I would: 1) Try the experiment with other Carbonates. I would predict that even for other carbonates, as the mass of Carbonate is increased the amount of Carbon Dioxide produced increases. This relation will be directly proportional. To prove this I will do the calculations for Magnesium Carbonate. Magnesium Carbonate Hydrochloric Acid Magnesium Chloride Water Carbon Dioxide MgCO3 2HCl MgCl2 H2O CO2 1 2 1 1 1 84g 73g 95g 18g 24dm3 g of MgCO3 produces 24dm3 of CO2 as 1 mole of any gas at room temperature and pressure occupies 24dm3. g of MgCO3 produces 286cm3 of CO2 g of MgCO3 produces 228cm3 of CO2 g of MgCO3 produces 171cm3 of CO2 g of MgCO3 produces 114cm3 of CO2 g of MgCO3 produces 57cm3 of CO2 Therefore it can be said that for any carbonate the relationship will be exactly the same, i.e. as the mass of Carbonate is increased the amount of Carbon Dioxide produced increases directly proportionally. 2) Do the whole experiment again but using various different pieces of apparatus. I would do an experiment, which doesnt include water, therefore no gas can be lost. Apparatus required: * Syringe * Trough * Delivery Tube * Round bottomed flask * Calcium Carbonate * 2M Hydrochloric acid * Balance * 5cm Tubes Method * Set apparatus as in diagram below * Place a piece of paper on the balance and zero it * Measure out the required mass of Calcium Carbonate * Pour massed amount of Calcium Carbonate into tube * Place tube in the lip of the round bottomed flask * Connect the delivery tube to the flask * Tap gently so that the tube falls into the acid * Shake fairly gently, making sure you are holding the delivery tube so that it doesnt dislodge from under the measuring cylinder. * When all the Calcium Carbonate has reacted record the final volume of gas obtained.