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GCSE CHEMISTRY COURSEWORK: Titrations
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Titrations Introduction: In this experiment we are going to be testing to see which antacid tablet works the best in helping us get rid of stomache aches. From our preliminary experiment, the results we got told us that Rennie was the best antacid tablet with the most accurate results and was also the best tablet in strength. Neautralisation basically occurs when the right amounts of acid and alkaki react. Aim: The aim of this experiment is to find out which antacid tablet works the best in removing stomache aches the quickest. Key Factors: In...
weights and by taking 1g pf each tablet our results would be fair.

To make our method more accurate we could test each tablet on people who have stomache aches and see which one is more effective. We could also test the pH of a stomache and see which tablet would be most suitable.

Another improvement to our experiment would be to get slices of the stomache and let it grow to see what happens and then test the tablets. We could also do the test more times and see if we get the same results.

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Introduction In this... Introduction In this assignment I will investigate hazard and prevention. This is three tasks assignment. In task one I will make a checklist and definition of checklist and why we should make a checklist for any place. For task two I have given an A4 sheet with tropical image of accidents. For this task I need to find out these accidents and write how I could prevent them. Fro task three I need to write all about hazards and anything related to this. Task one In this task I am going to make a checklist for my chemistry lab. Checklist is a tool to ensure all-important steps or actions in an operation have been taken. Checklist contains items important or relevant to an issue or situation. Checklist is a safety list. Checklist is a list of different equipment in a lab or home or office. Make sure that all the equipment listed in the checklist and it should check once or twice a year. A checklist helps us to find out what type of equipment we get a specific place, such as lab or home. If I don¡¦t have a checklist, than I can¡¦t tell what I have gets in a place such as lab or home. Checklist often confused with check sheet. Check sheet is a simple data-recording device. The check sheet is custom designed by the user, which allow him or her to readily interpret the result. I am going to make a checklist about G4 Chemistry laboratory. I will check each item once a year. Category Date of checking Any thing wrong Yes No Action Job Done First Aid Eye wash 20 /08/2002 Water line block Call an plumber Clear the line. Fire fighting Equipment Fire Extinguisher Fire Blanket Fire Alarm Fire Exit Sand Bucket Main Equipment Gas guard Electric power supply Gas tapes Electric sockets Equipment Broken bucket Bin bag Water bath Oven Special equipment Distilled water Eye/body protection Lab coat Goggle Spectacles Face shield Experiment safety Hazards warning sign Safety screen Task two a I have given an A4 sheet paper where they gave me a typical image of an accident waiting to happen in the laboratory. My task is to identify these accidents and explain how I could prevent them happening. List of the accident may happen in this laboratory: 1. A boy doing an experiment where chemicals will fall of on his body. And he didn¡¦t wear an eye protection. And height of the object is not appropriate for him. 2. A girl doing en experiment but her long hears were untied, under her hair there is a Bunsen burner with fire. 3. Middle of the class room there is water on the floor. 4. A boy opens an electric socket without teacher permission. He might get electric shock. 5. All students do not wear eye protection. 6. A girl playing with the rubber band and disturbing other to do their experiment. 7. A girl doing experiment but her test tube face at her chemicals will go on to her body. 8. A girl doing an experiment but her test tube faced straight to up. Hot chemicals may explore and fall on to her body. 9. A girl holding a hot bicker without a glove. 10. A girl looking to other girl and mistakenly she put her hand up on the hot gorse. 11. A boy carrying box but he can¡¦t see anything what happen to front. 12. Main exit door blocked by boxes. If fire in the room no one can get out. 13. Teacher given demonstration about chemical where students were too close and there is no safety screen. None of these students wearing goggle. 14. A girl put an iron stand at the edge of the tale. It could fall onto someone¡¦s foot. 15. Some one put a biker up on the gorse at the edge of the table. 16. Bunsen burner left with blue fire. I could prevent these accidents by: 1. Height of the object must be appropriate for him. And he must wear a goggle to do chemical experiment. 2. This girl must tie her hear up and when she does not use Bunsen burner she must left it with yellow coloured fire. 3. Clean the water as soon as possible. Otherwise someone may slip n the floor. And it may break their leg or hip. 4. Teacher must warn students about electric socket that students never try to open an electric socket. It is dangerous to get an electric shock. 5. All students doing various experiments, but none of them use eye protection. Chemicals or other thing could spill in to the eye. To prevent this happen teacher must tell students advantage of wearing a goggle which can save my eyes to have any damages. 6. Tell her play outside. 7. Test tube must not face to you or other people, because chemical may explore and go onto your body. 8. Test tube must put diagonally, because if test tube put straight up and chemicals heated than chemical will explore and could fall onto your body. 9. If anyone needs to hold some thing hot they must use glove. Because otherwise they might burn themselves. 10. If anyone does any experiment they must concentrate with their experiment. 11. Tell him to remove these boxes after the class. 12. Clear the door way. 13. Use a safety screen and student must wear goggle. 14. Put the iron stand middle of the table. 15. Put bicker and gorse middle on the table. 16. Bunsen burner must be left with yellow flame. Task two b In this task I will write about three accident and necessary emergency procedures could be used in these accident. There are the accidents: ƒ¾ Chemical in the eye ƒ¾ Chemical burn ƒ¾ Electric shock Chemical in the eye: splashes of chemicals in the eye can cause serious injury if not treated quickly. Recognition of chemicals there may be: "žÃ Intense pain in the eye "žÃ Inability to open the injured eye "žÃ Redness and swelling around the eye "žÃ Copious watering of the eye "žÃ Evidence of chemical substance or containers in the immediate area. Treatment: First thing do not allow the casualty to touch the injured eye or forcibly remove contact lens. Hold the affected eye under gently running cold water for at least ten minutes. Make sure that you irrigate both sides of the eyelid thoroughly. If the eye is shut in a spasm of pain, gently but firmly pull the eyelid open. Be careful that contaminate/rotten water does not splash the uninjured eye. Ask the casualty to hold sterile eye pad or any clean pad or non-fluffy materials over the injured eye. Than take or send the casualty to the hospital. Chemical burn: certain chemicals may irritate, harm or be absorbed through the skin, causing widespread and some times fatal damage. Recognition of chemical there may be: "žÃ Evidence of chemical in the vicinity "žÃ Intense, stinging pain "žÃ Later, discolouration and swelling of the affected area. Treatment: Never attempt to neutralise acid or alkali burn unless trained to do so. Do not delay starting treatment by searching for an ambulance. First make sure that injured area is safe. Ventilate the area and remove the casualty if necessary. And seal the chemical container if possible. Flood the affected area with water to disperse the chemical and stop the burning. Do this at least 20 minutes. Gently remove the pollute clothing during flooding the injury. Take or sand the casualty to hospital. Give the details about chemical to medical person. Electric shock: Domestic current, as used in home, office, college lab etc, can caused serious injury and even death. Action: do not touch the casualty if they contact with electrical current, he will be ¡§live¡¨ and risk electrocution. Do no use anything metallic to push away the electrical source. Try to switch off the socket or main power, if you can¡¦t switch off than stand on dry insulating materials such as a wooden box or telephone guide. Push the casualty¡¦s limbs away from the source with a broom, wooden chair or stool or push the push the source from the casualty, whichever is easier. If the casualty is unconscious, open the airway check for breathing and be ready to place them in recovery position. Cool if there any burn with cold water. Dial 999 for an ambulance. If the casualty seems to be unharmed, advise them to rest. Observe them closely and, if in doubt, call a doctor. If the hart stops apply the ABC Airway, Breathing and Circulation signs of life of resuscitation until a normal heartbeat returns or specific medical treatment is given. Task three Hazard & Risk The term "risk" is often confused with "hazard". A high voltage power supply, a sample of radioactive metal, or a toxic chemical may present a hazard, meaning that they present the potential for harm. Concentrated acids, for example, clearly present the hazard to the user of serious burns if they are handled incorrectly. A hazard is something with the potential to cause harm of life e.g. this can be a substance, part of a machine, form of energy, method of work or a situation. Harm includes death, injury, physical or mental ill health, damage to property, loss of production, damage to the environment or any combination of these. Risk is a measure of the likelihood that the harm from a particular hazard will occur, taking into account the possible severity of the harm. The risk is the probability or chance that the hazard posed by the chemical will lead to injury. Thus, concentrated sulphuric acid is a hazardous chemical; because it is very corrosive and reactive. However, provided it is handled in an appropriate way the risks it poses may be small. For the risk to be real: "žÃ The threat must exist. "žÃ There is likely to be magnitude of effect. "žÃ There is potential for occurrence. It is thus evident that hazards are something we can do little about. The hazard posed by a carcinogen, a concentrated acid or an explosive substance is inherent properties of the material. The risks they pose, however, can be and should be! minimised by initially preparing a suitable risk assessment. Risk Assessment is the process of analysing the level of risk, considering those in danger, and evaluating whether hazards are adequately controlled, taking into account any measures already in place and any work practices that may be in force. I have to fill a risk assessment for my Physics experiment. Sample of that risk assessment form as below: Components of Hazards There are number of components to consider in defining hazard: ľ Intrinsic properties of the hazard. ľ The nature of the equipment or from of the material such as vapour, mist, liquid etc. ľ The exposure-effect relationship. ľ The pathways and frequency of use ľ Aspects of worker behaviour the affect exposure to the hazard. ľ Mechanisms of action. Type of Hazards: There are different types of hazards: Chemical hazard: through a variety of action, chemicals can cause damage to health and property. Some of these actions are explosive, flammable, corrosive, oxidation, poisoning, toxicity, and carcinogenicity. Biological Hazard: mainly from infection or allergic reaction. Biological hazards include viruses, bacteria, fungi and other organism. Some biological hazards such as AIDS or hepatitis B are potentially life threatening. Physical hazards: these include noise, radiation such as ionising, electromagnetic or non-ionising, heat, cold, vibration and pressure. Ergonomic hazards, psychological hazards, Lateral water hazards, EM hazards, health hazards etc. Components of Risk; ľ Individual variation in susceptibility. ľ The numbers exposed. ľ The degree of individual risk. ľ The possibility of elimination of a less hazardous substance or process. ľ The possibility of achieving of the hazard. ľ Public opinion and pressure groups. ľ Social responsibility. Perception of Risk: People judge risks differently. Judgments are made on the ease of recall and imagining. For example, the role of the media in bringing risk issues such as AIDS or asbestos to public attention in one exercise of this judgment. While risk analyses will provide some estimate of a risk in numerical terms, presentation of quantitative facts on risk rates often does not work well. Statistical expressions of risk are only one dimension of risk, and these may be irrelevant to lay people who view risk qualitatively. Warning signs represent a hazard level between Caution and Danger. A warning indicates a potentially hazardous situation, which, if not avoided, could result in death or serious injury. All the chemicals in the laboratory must have warning sign and labelled, because without a warning sign or label no one will know is it a corrosive, flammable or other dangerous chemical. To be safe in a laboratory than all chemical must be label and must have a warning sign. Example of some warning sign: A survey carried out in school science laboratory publisher in education in science. The result of that survey most common accident in the laboratory as below: Accident Percentage Chemicals in the eye 23% Chemicals on the body 21% Cuts 20% Burn & scalds 15% Dropping, falling, slipping, lifting, knocking 7% Chemicals in mouth 4% Inhalation 4% Animal bites 3% Explosions 2% Electric shock 1% Most common accidents in laboratory show in the pie chart as below; The result of the survey tell that chemical in the, is the most common, because students does not follow the safety rule. In the safety rule they give everything what student should do when they enter in a laboratory. Before get this result I thought cut will be the height common accident, but in this result show chemical in the eye is the most common accident. This because students don¡¦t understand the important of wear eye protection. They didn¡¦t listen to their teacher. The safest place from accident is science laboratory, because they have rule which you must need to follow. And mostly accident happened in home, because we don¡¦t have any rule in home. That way in the home there are most accident happened. For safe in laboratory they made a safety rule. A sample of a safety rule in science laboratory is below: To be safe in the laboratory we must follow the safety rules and we must have hazards warning sign and label. And minimise the risk we should do risk assessment. Before using a lab first thing to do is make a checklist of the entire item in the lab. Than check these once or twice a year. Safety check is very important because if something wrong in the lab than from safety check we could know about it. Safety check helps us to find out any fault or any thing change we need to do. In your home you also need a checklist, because if any thing stolen from your home police will ask you what the things stolen. In this time you need a checklist. You also need checklist for checking is your all machinery or other things work properly such as your washing machine, freezer etc. so a checklist very important for any particular place.   

Introduction In this assignment I will investigate hazard and prevention. This is three tasks assignment. In task one I will make a checklist and definition of checklist and why we should make a checklist for any place. For task two I have given an A4 sheet with...

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Rate Of Reaction in... Rate Of Reaction in Sodium Thiosulphate and HCl Plan in this experiment I am investigating the rates of reaction, and the effect different changes have on them. The rate of reaction is the rate of loss of a reactant or the rate of formation of a product during a chemical reaction. A rate of reaction is measured by dividing 1 by the time taken for the reaction to take place. There are five factors which affect the rate of a reaction, by the collision theory of reacting particles: temperature, concentration of solution, pressure in gases, surface are of solid reactants, and catalysts. Aim: - my aim is to see the effects of a change in temperature and concentration on the rate of a reaction. The reaction that will be used is: Sodium Thiosulphate + Hydrochloric Acid Na2S2O3 aq + 2HCl aq Sodium Chloride + Water + Sulphur Dioxide + 2NaCl aq + H2O l + SO2 g + Sulphur S s Two experiments will be carried out "“ one changing the temperature while everything else remains constant and one varying the concentration while keeping everything else constant. Both the sodium thiosulphate and the Hydrochloric acid are soluble in water, so the concentration of either can be changed. temperatures and concentrations to use during my preliminary series of experiments "“ 50cm3 of sodium thiosulphate solution and 5cm3 of hydrochloric acid as the experiment one con 1 mol/dm3 of HCl acid concentration will be fixed 10-35g/dm3 of sodium thiosulphate all of these concentrations will be tested in turn going up in steps of 5g/dm3 20-70°C temperature all of these temperatures will be used going up in steps of 10°C Concentrations of 5, and 40 g/dm3 of thiosulphate were available to me but my preliminary work showed that the 5 g/dm3 and 40g/dm3 were too slow and fast respectively in reacting to be worth testing. Similarly any temperature below 20°C reacted too slowly, and 80°C and 90°C reacted too quickly to be worth including in my final results. Using my preliminary experiments I decided on using the following apparatus: 1 thermometer 1 beaker 2 measuring cylinders 1 conical flask 1 tripod 1 gauze 1 heatproof mat 1 stopwatch 1 Bunsen burner X board 1 pair of tongs 1 pair of goggles 1 apron Method: - Experiment 1 - Changing the concentration 5 cm3 of HCl at concentration 1 mol./dm3 and 15 cm3 of sodium thiosulphate at varying concentrations "“ 10 to 35 g/dm3 are poured out into two measuring cylinders and then poured into a conical flask, which is placed on top of a board marked with letter X. The stopwatch will now be started. When the mixture has turned sufficiently cloudy so that the letter X can no longer be seen the stopwatch will be stopped and the time will be recorded. The experiment is repeated with all the concentrations. The whole procedure is then repeated. Experiment 2 "“ Changing the temperature 5 cm of HCl at concentration 1 mol./dm3 and 15 cm of sodium thiosulphate at varying concentrations "“ 10 to 35 g/dm3 are poured out into two measuring cylinders. A beaker is half filled with hot water from a tap. The water is placed on top of a Bunsen on a blue flame and the two measuring placed inside the water bath. The water is heated to the necessary temperature 30°C to 70°C then the two measuring cylinders are taken out and the contents of both are poured into a conical cylinder. The time it takes for the X to disappear is timed and recorded. The experiment is repeated using all the temperatures. The entire procedure is the repeated. Repeat results and averages will be taken to improve the credibility of the findings, and present solid grounding for the final conclusion. The repeat results will help to iron out any anomalies and the average will give a good summary of the results of the experiment. However if one set of results is entirely different to the other, a third experiment will be performed to replace the anomalous set of results. Safety "“ A pair of goggles will be worn during the heating part of the experiment in order to protect the eyes. An apron will also be worn to protect the skin and clothing. When handling hot beakers and measuring cylinders a pair of tongs will be used. A gauze and heatproof mat will be used while heating to avoid any damage to the equipment. Fair Test - In order for my findings to be valid the experiment must be a fair one. I will use the same standard each time for judging when the X has disappeared. I will make sure that the measuring cylinders for the HCl and thiosulphate will not be mixed up. The amount of HCl will be 5 cm3 each time, and the amount of thiosulphate will be fixed at 15 cm3. During the heating stage of the experiment, a blue flame will be used throughout. Also the same Bunsen burner and gas tap will be used to maintain continuity. All of these precautions will make my final results more reliable and keep anomalies at a minimum so thus make the entire investigation more successful. Prediction "“ I predict that as the temperature is increased the rate of reaction will increase. I also predict that as the concentration of the sodium thiosulphate increases the rate of reaction will increase. This means that both graphs drawn up in my analysis will have positive correlation, and will probably be curved as the increase in rate of reaction will not be exactly the same as the concentration temperature is increased. This can be justified by relating to the collision theory. When the temperature is increased the particles will have more energy and thus move faster. Therefore they will collide more often and with more energy. Particles with more energy are more likely to overcome the activation energy barrier to reaction and thus react successfully. If solutions of reacting particles are made more concentrated there are more particles per unit volume. Collisions between reacting particles are therefore more likely to occur. All this can be understood better with full understanding of the collision theory itself: For a reaction to occur particles have to collide with each other. Only a small percent result in a reaction. This is due to the energy barrier to overcome. Only particles with enough energy to overcome the barrier will react after colliding. The minimum energy that a particle must have to overcome the barrier is called the activation energy, or Ea. The size of this activation energy is different for different reactions. If the frequency of collisions is increased the rate of reaction will increase. However the percent of successful collisions remains the same. An increase in the frequency of collisions can be achieved by increasing the concentration, pressure, or surface area. Concentration "“ If the concentration of a solution is increased there are more reactant particles per unit volume. This increases the probability of reactant particles colliding with each other. Pressure - If the pressure is increased the particles in the gas are pushed closer. This increases the concentration and thus the rate of reaction. Surface Area "“ If a solid is powdered then there is a greater surface area available for a reaction, compared to the same mass of unpowdered solid. Only particles on the surface of the solid will be able to undergo collisions with the particles in a solution or gas. The particles in a gas undergo random collisions in which energy is transferred between the colliding particles. As a result there will be particles with differing energies. Maxwell-Boltzmann energy distribution curves show the distribution of the energies of the particles in a gas. The main points to note about the curves are: 1. There are no particles with zero energy. 2. The curve does not touch the x-axis at the higher end, because there will always be some particles with very high energies. 3. The area under the curve is equal to the total number of particles in the system. 4. The peak of the curve indicates the most probable energy. The activation energy for a given reaction can be marked on the distribution curve. Only particles with energy equal or greater than the activation energy can react when a collision occurs. Although Maxwell-Boltzmann distribution curves are for the particles in a gas, the same distributions can be used for the particles in a liquid or solid. Effects of a temperature change - The graph below shows Maxwell-Boltzmann distribution graphs for a fixed mass of gas at two temperatures "“ T1 and T2, where T2 is roughly 10°C higher than T1. The total area under the curve remains the same, since there is no change in the number of particles present. A small increase in temperature causes significant changes to the distribution energies. At the higher temperature: 1. The peak is at a higher energy. 2. The peak is lower. 3. The peak is broader. 4. There is a large increase in the number of particles with higher energies. It is the final change that results increase in rate, even with a relatively small increase in temperature. A small increase in temperature greatly increases the number of particles with energy greater than the activation energy. The shaded areas on the energy distribution curves show this. Effect of a catalyst - A catalyst works by providing an alternative reaction pathway that has lower activation energy. A catalyst does not alter the Maxwell-Boltzmann distribution. Because a catalyst provides a reaction route of lower activation energy, however, a greater proportion of particles will have energy greater than the activation energy. Secondary Sources Used: AS Level Chemistry Textbook kinetics module The Internet Dr. Jones's Chemistry Lessons Information sheets from Dr. Jones Obtaining Evidence Temp.°C Time 1 s Time 2 s Average s 20 110.67 107.42 109.045 30 100.13 103.34 101.735 40 64.20 65.92 65.06 50 45.34 37.73 41.535 60 30.12 33.18 31.65 70 18.92 16.34 17.63 Concen.g/dm3 Time 1 s Time 2 s Average s 10 222.63 224.38 223.505 15 150.90 147.03 148.965 20 105.25 105.97 105.61 25 66.04 68.75 67.395 30 55.63 56.1 55.865 35 27.32 25.96 26.64 Temp.°C Rate of Reaction 1s-1 Rate of Reaction 2 s-1 Average s-1 20 0.00904 0.00931 0.00917 30 0.00999 0.00968 0.00983 40 0.01558 0.01517 0.01537 50 0.02206 0.02650 0.02428 60 0.03320 0.03014 0.03167 70 0.05285 0.06120 0.05703 Concen.g/dm3 Rate of Reaction 1s-1 Rate of Reaction 2 s-1 Average s-1 10.00000 0.00449 0.00446 0.00447 15.00000 0.00663 0.00680 0.00671 20.00000 0.00950 0.00944 0.00947 25.00000 0.01514 0.01455 0.01484 30.00000 0.01798 0.01783 0.01790 35.00000 0.03660 0.03852 0.03756 Temp.°C Rate of Reaction 1s x1000 Rate of Reaction 2 s x1000 Average s 20 9.04 9.31 9.17 30 9.99 9.68 9.83 40 15.58 15.17 15.37 50 22.06 26.50 24.28 60 33.20 30.14 31.67 70 52.85 61.20 57.03 Concen.g/dm Rate of Reaction 1s x1000 Rate of Reaction 2 s x1000 Average s 10 4.49 4.46 4.47 15 6.63 6.80 6.71 20 9.50 9.44 9.47 25 15.14 14.55 14.84 30 17.98 17.83 17.90 35 36.60 38.52 37.56 Analysis In this experiment I have found that as the temperature and concentration is increased the time taken for the reaction to take place decreases. This means the rate of reaction increasers as it takes less time for a reaction to take place, so more take place per second. In the temperature experiment the time taken for a reaction to take place decreased by roughly 10 to 15 seconds for every 10°C increase in temperature, with the one anomaly being the 30°C reading. There is also a trend in the increase in rate of reaction as the temperature increases. The difference is always more or less 0.02 s-1, with the same exception. Using the graphs, with lines of best fit, I can draw a conclusion from my experiment. Firstly I can see that with the "time" graphs that plot temperature and concentration against time taken for the reaction to take place the graphs have negative correlation in both cases, meaning that as the temperature concentration increased the time taken for the reaction to take place decreases. The time graph for the temperature experiment has a much steeper curve than the one for the concentration experiment, meaning that the decrease in time taken for the reaction was far more rapid. Naturally, the above means that the both the graphs plotting rate against temperature and concentration have positive correlation "“ as the temperature and concentration are increased so does the rate of reaction. This is because when the temperature is increased the particles will have more energy and thus move faster. Therefore they will collide more often and with more energy. Particles with more energy are more likely to overcome the activation energy barrier to reaction and thus react successfully, and when solutions of reacting particles are made more concentrated there are more particles per unit volume. Collisions between reacting particles are therefore more likely to occur. The graph for concentration shows that when the concentrations were relatively low 10, 15, 20 g/dm3, the increase of rate x1000 was also fairly small increasing from 4.47 to 6.71 to 9.47. There was then a gradual increase in the difference, and between 30 and 35 g/dm3 the rate more than doubled from 17.90 to 37.56s-1. This shows that there are far more collisions at a concentration of 35 g/dm3 than at 30 g/dm3. The graph plotting time against the rate of reaction x1000 shows that the difference of rate between increasing temperatures excluding the anomaly of 30°C was pretty much regular, increasing in steps of 6-10 9.17 to 15.37 to 24.28 to 31.67. However, once again there is a giant gap in the last temperature increase "“ at 60°C the RoR x1000 is 31.67 s-1, and at 70°C it is 57.03 s-1. For this to fully make sense it is necessary to recap the collision theory briefly: For a reaction to occur particles have to collide with each other. Only a small percent result in a reaction. This is due to the energy barrier to overcome. Only particles with enough energy to overcome the barrier will react after colliding. The minimum energy that a particle must have to overcome the barrier is called the activation energy, or Ea. The size of this activation energy is different for different reactions. If the frequency of collisions is increased the rate of reaction will increase. However the percent of successful collisions remains the same. An increase in the frequency of collisions can be achieved by increasing the concentration, pressure, or surface area.   

Rate Of Reaction in Sodium Thiosulphate and HCl Plan in this experiment I am investigating the rates of reaction, and the effect different changes have on them. The rate of reaction is the rate of loss of a reactant or the rate of formation of...

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I am measuring the... I am measuring the rate of reaction how fast a reaction takes of sodium thiosulphate and hydrochloric acid. There are different variables I could use to see the change in the rate of reaction. These include temperature, concentration or catalysts. I am going to do two experiments, one changing the temperature and one changing the concentration of the sodium thiosulphate. This is how they will be done. Planning Experimental Procedures Equipment Sodium thiosulphate Na S O of different concentrations Hydrochloric acid HCl Tile marked with a cross Measuring cylinder x2 Beaker x2 Bunsen Tripod Test tube x2 Stopwatch Thermometer As the diagrams show, firstly I will measure the right amount of sodium thiosulphate and hydrochloric acid into two separate test tubes. If it is needed, these will then be put into water and heated with a Bunsen burner and tripod until they are up to temperature, which will be measured with a thermometer in the water. They will then be put into the beaker. Firstly, the experiment will be done with the substances at room temperature. This means that the beaker will be filled with Na S O and HCl via two measuring cylinders and placed on the tile marked with a cross. The amount of Na S O and HCl being put in the beaker will be determined by prior tests, but they will only need to be quite small amounts. As soon as the two substances are mixed together, the stopwatch will start timing and it will stop when the cross is obscured. When the substances need to be heated, they will be put in separate test tubes and heated in a beaker of water as above. They will be mixed together when up to temperature. One of the experiments will show the difference temperature makes and the other will show the difference the concentration of the sodium thiosulphate makes. During the experiments, goggles and aprons will be worn at all times for safety. The tests will be made fair by the fact that only one thing will be changed each time "“ the temperature or concentration of the sodium thiosulphate. We presume that when the concentration of the Na S O is increased, the rate of reaction will be higher. This is because if there are more molecules, they are more likely to collide and react. However, the collision theory says that a very small percentage of these collisions results in a reaction. This is because of an energy barrier. Only those particles with enough energy to overcome the energy barrier will react when they collide. So, if the frequency of collisions is increased, the rate of reaction will increase. However, the percentage of successful collision will remain the same. The particles go through random collisions in which energy is transferred between the colliding particles and this leads to particles with differing energies. The distribution of the energies of a particle of gas is shown by the Maxwell-Boltzmann energy distribution curve, shown below. We would also presume that when the temperature is increased it will have the same effect. This is because the molecules will collide more often and with greater energy and so will be more likely to successfully react because their bonds break. For an average reaction a 10 C temperature rise doubles the rate of reaction because about twice as many particles possess the necessary activation energy. The next diagram shows Maxwell-Boltzmann distribution curves for a fixed mass of gas at two temperatures T and T where T is about 10 C higher than T . The total area under the curve remains the same since there is no change in the number of particles present. So, I predict that in the experiment were the temperature is varied, the rate of reaction will go up as the temperature goes up. In the experiment where the concentration of the thiosulphate is to be varied, I expect the rate of reaction to go up as the concentration goes up. If the concentration doubles, I would expect the rate of reaction to double and if the concentration is zero I would expect the rate of reaction to be zero. In the graph showing temperature compared to rate of reaction, I would expect there to be negative correlation and in the graph showing concentration compared to rate of reaction, I would expect there to be negative correlation. However, it remains to be seen if the results will follow this theory. Here are the results tables that will be used: Temperature 1st results 2nd results Average Rate Of Reaction C seconds seconds seconds seconds Room approx.20 30 40 50 60 70 This is for the first half of the experiment where everything will be kept the same except the temperature which will range from 20 C to 70 C. It is hoped that there will be sufficient time for two experiments and an average will be calculated afterwards. The concentration of the sodium thiosulphate used throughout will be 30g/dm. Concentration 1st results 2nd results Average Rate Of Reaction g/dm seconds seconds seconds seconds 15 20 25 30 35 40 This is the other section to the experiment where everything will be constant apart from the concentration of the sodium thiosulphate. It has been decided that a concentration of no less that 15g/dm will be tested because any less than this would probably take too long. The hydrochloric acid and the sodium thiosulphate will not be heated and the tests will be done at room temperature, usually around 20 C. The experiment will be done twice or three times if possible and the results will be made fair by the fact that only one thing will vary each time. Goggles and aprons will be worn at all times for safety. It has been decided that 5ml of HCl and 20ml of Na S O will be used. Obtaining Evidence These are the results of the experiments: Temperature 1st results 2nd results Average Rate Of Reaction C seconds seconds seconds secs Room approx.20 74.5 69.9 72.2 13.85 30 38.1 38.3 38.2 26.18 40 35.9 39.4 37.65 26.56 50 20.7 18.1 19.4 51.55 60 12.3 9.9 11.1 90.09 70 5.9 5.2 5.55 180.18 Concentration 1st results 2nd results Average Rate Of Reaction g/dm seconds seconds seconds secs 15 125.2 123.5 124.35 8.04 20 74.5 69.9 44.2 13.85 25 53.6 51.2 52.4 19.08 30 49.6 51.6 50.6 19.76 35 45.7 48.8 47.25 21.16 40 22.6 30.5 26.55 44.35 Analysing evidence and drawing conclusions All results have now been obtained and they seem to be quite good, all showing correlation. As was hoped at the start, a repeat was managed for each test and an average worked out from those figures. The results were recorded with decimal place and the averages and rate of reactions are to two decimal places. The rate of reaction is the key thing being looked at in this experiment and this is how it was calculated: 1 Time taken for cross to be obscured This figure was then multiplied by 1000 to make it easier to deal with. The figures have all been rounded to two decimal places. My predictions have been correct. When the concentration of the sodium thiosulphate has gone up, as the first part of the experiment shows, the rate of reaction goes up. When the temperature goes up, as the second results table shows, so does the rate of reaction. This is what was expected and therefore makes it highly unlikely that there have been any major mistakes, although all results are obviously not perfect. The next three pages are graphs. Graphs one and two relate to the first table of results and graph three relates to the second table. The reason there are two graphs for the first table is that one shows time taken for cross to be obscured and the other shows rate of reaction. Rate of reaction is what is being investigated and so only a rate of reaction graph was needed for table two. There are two graphs for the first results table to show the difference in time taken and rate of reaction i.e. the time taken for cross to be obscured shows negative correlation while graph two shows positive correlation. By drawing a line of best fit on the rate of reaction graphs, we can see that there are no results that are obviously completely wrong. With both graphs the last result is suprisingly high, and this can be seen on the results table as well. Evaluating Evidence The procedure used was good and produced good results but it could have been improved and these will be listed later. The results are mainly good, there are no odd results and everything came out as expected. This could mean that the experiment was done perfectly but it doesn't. Although all the average times and rates of reaction all conform to a pattern, they are not all evenly spaced and therefore are probably not perfect. As an example, in the first experiment, where the temperature was being varied, the rates of reaction of 30 C and 40 C were 26.18secs and 26.56secs respectively. This was only an increase of 0.38secs compared to an increase of 90.09secs for 60 C to 70 C from 90.09secs to 180.18secs . Clearly this is an enormous difference and disproportionate. The results could be correct but the results do appear to nearly double each time, except for in this instance. There are similar examples from the second experiment but they are not as obvious. Improvements that could be made if the experiment was repeated: When doing the results that took less time some took around five seconds, it would have been more accurate to have two people so one person could put the substances together while the other person started timing Obviously it would have been good to have done more repeats. Two tests were managed each time but if one had been wrong this could have dramatically changed the average time and therefore rate of reaction. Increasing the surface area of a reactant will increase the rate of a reaction. This is because the reacting particles can only collide with he surface of the solid and the particles within the solid cannot react until those on the surface have reacted and moved away. Powdered calcium carbonate has a much larger surface are than the same mass of marble chips and therefore will react more quickly. All in all I think this was a good experiment and the best that could have been done with the time and resources available. The results supported my predictions and they seem to be fairly reliable results. Aim : We did 4 experiments to find out how the rate of reaction changes with differing concentrations of Sodium Thiosulphate, Hydrochloric Acid and water. As an inert and stable liquid, water was used to alter concentration of Sodium Thiosulphate without changing the end amount of solution. All the atoms in a water molecule have a full outer shell, so they would not react with the other chemicals. WATER IS USED TO SLOW THE REACTION SO THAT IT IS EASIER TO TIME HOW LOG   

I am measuring the rate of reaction how fast a reaction takes of sodium thiosulphate and hydrochloric acid. There are different variables I could use to see the change in the rate of reaction. These include temperature, concentration or catalysts. I am going to do two experiments, one...

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