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to investigate how the concentration affects the rate of the reaction

Extracts from this document...

Introduction

CHEMISTRY COURSEWORK AIM: To investigate how the concentration of an acid affects the rate of a reaction PLANNING SAFETY MEASURES I will make my method safe by doing the following things; * Clearing all bags from the lab because they will cause me to trip * Wear a laboratory coat to protect my clothes from acid * I will work on a flat surface to make sure all my measurements are accurate * I will tie my hair back to prevent my hair from getting in contact with the acid * I will not eat or drink anything in the laboratory because some of these substances may affect the product or the investigation as a whole BACKGROUND INFORMATION In everyday life, reactions always take place. Examples are; 1. The fermentation of milk. 2. The frying of an egg. 3. Rusting of iron. 4. The formation of a salt solution. All reactions take place in different times. They can be very fast (frying of an egg), or quite slow (rusting of iron). A reaction can be defined as a process that involves changes in the structure and energy content of atoms, molecules, and ions. In a reaction a number of things are happening for a product to be formed. Molecules have to collide with each other and stick together for a product to be formed. Collisions do not always take place. I know this because not all reactions are fast; some are very slow and will even take a month before I notice any changes in the substance. For a reaction to take place, bonds between substances have to be broken so that new bonds can be formed. Energy (which can be in any form) which is needed to start a reaction is known as the activation energy The rate of a reaction can be defined as the speed which a chemical reaction takes place. ...read more.

Middle

To find out the different amounts of acid and water I use for each molarity, I will multiply the molarity by the volume and divide by the original concentration of the acid used in the preliminary experiment like I have done below: Acid concentration (m) Amount of acid (ml) Amount of water (ml) 2 16 0 1 (16*1)/2=8 16-8=8 1.25 (16*1.25)/2=10 16-10=6 1.5 (16*1.5)/2=12 16-12=4 0.75 (16*0.75)/2=6 16-6=10 0.5 (16*0.5)/2=4 16-4=12 OBTAINING EVIDENCE As I was carrying out my experiment, I made sure I carried out all the safety measures I listed before. I have used a table for recording my results because when data is put on a table, it puts the data into different boxes and each result can be easily and quickly found on a table. When I carried out my experiment, I had to repeat some of the readings because they were not within the 10% range and due to that, I had to repeat the experiment. The first readings I took had the concentration of 1molar. Mass of magnesium used Volume of acid used Volume of water used Time Hydrogen given off 1st reading 2nd reading 3rd reading 4th reading 0.06 8 8 20 20 20 19 20 40 30 30 29 30 60 38 39 36 40 80 44 46 40 47 100 50 52 45 52 120 54 56 47 56 140 56 59 47 58 160 58 60 stopped 60 180 60 61 60 200 61 61 Stopped 220 61 Stopped 240 stopped I noticed that my third set of results were wrong because they were not within the 10% range. I knew this was an error. I had put the stopper in and some of the gas had come off. So due to this, I had to re-take my readings. The second set of readings was with the concentration of 1.5molar of acid Mass of magnesium used Volume of acid used Volume of water used Time Hydrogen gas given off 1st reading 2nd reading 3rd ...read more.

Conclusion

My results are not very accurate because I had some anomalous results but my results were taken three times per molarity, so this proves that my results have a degree of accuracy. Also, they were all within a 10% range so this proves that the results can be used. IMPROVEMENTS If I had a chance to repeat my experiment, I would change the apparatus used. I would have also included a thermometer to make sure the temperature in the laboratory remains constant. I would also need a scale that can measure up to four decimal places to allow all my results to be very accurate. I would want to add more concentrations to the experiment, to have a better knowledge of how the reaction takes place. These points would not only make my results very accurate, it will allow my evidence to be more reliable because the more accurate my measurements are, the more accurate my results are leading to better graphs and less anomalous results. My test was not fair because the temperature was not constant. Also the measurement of the magnesium was not very accurate because two decimal places are not the best of measurements. The mass could be 0.061 or 0.064 and it will be measured as 0.06 when the second mass is heavier. I did experience some difficulty in the experiment. I did not know how to prevent the plentiful loss of hydrogen during the experiment. I experienced this because as I was pouring in the hydrochloric acid into the test tube, it had started reacting with the magnesium giving off hydrogen gas. IMPROVEMENTS TO THE EXPERIMENT I could use a thistle funnel and a two holed stopper. The experiment setup will look like this; The funnel will be used to pour the hydrochloric acid into the test tube instead of pouring the acid into the test tube directly. It is better than the first method because it is safer and it also prevents/reduces the loss of hydrogen gas. ...read more.

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