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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
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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...
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

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My aim is to... My aim is to find out whether temperature has an effect on a rate of the reaction. I am going to be using the example of the reaction between Sodium Thiosulphate and Hydrochloric Acid. Prediction I predict that the higher the temperature, the more quickly the reaction will occur. This is because with heat, the particles of sodium thiosulphate and hydrochloric acid have more energy. This causes them to move around more. It works like this for all substances, not just those two. Chemical reactions require collisions, and if particles are moving around more quickly they are obviously more likely to collide and, as Collision Theory states, it affects the energy of the collision. I found out from preliminary research that the particle theory explains that chemical reactions require a collision between the particles of the reactants, at a certain speed and energy. I also found out that the factors that affect the rate of a reaction are:- § The surface area of the solid reactant if there is one § The concentration of the liquid substance. § The presence of a catalysts § The temperature In this experiment we are only interested in temperature. Where temperature is not high enough to provide energy for the particles to move at a high enough speed, the particles will just not react, and the higher the temp. the faster the particles move, so there are more collisions and so the faster the reaction will take place. At 20°C, I predict that the reaction will take a very long time to react. The reason I think this, is because although the particles will be moving around, they will not be moving at a high enough velocity for chemical reactions to occur, the particles must be travelling at a high speed and this requires energy. At this temperature I do not think that it will give the particles enough energy to convert into movement. At 30°C, I predict that the reaction will occur more quickly than that of 20°C. I predict this because there is more heat to provide energy to the particles of the reactants. This energy causes the particles of sodium thiosulphate and hydrochloric acid to move around more quickly, and naturally more collisions happen between the particles. Every jump upwards in the temperature of ten degrees I would expect the rate of the reaction to double. It should follow the Q10 rule. At the highest temperature of 60°c I would expect the reaction time to be very fast. I think this because the particles of sodium thiosulphate and hydrochloric acid will be moving around very quickly and at a high velocity so the chemical reaction will take place quicker. To summarise, at a cold temperature the reaction will take more time to happen. The particles of sodium thiosulphate and hydrochloric acid will not be moving around so quickly, meaning they are less likely to collide, therefore the reaction will take place in more time. Chemical reactions require a collision at a certain velocity, and if this velocity is not reached then the reaction will just not happen. With more heat, the particles have more energy, meaning they move around more. Collisions will be more likely to happen at a higher speed. Rate = Results. Temp. °C 20 30 40 50 60 Time s 1. 69 33 35 13 08 2. 62 32 35 12 12 3. 42 24 29 10 10 Average 65.5 32.5 29 11.66 10 Rate 0.015 0.030 0.034 0.085 0.100 Number = anomaly See graph 1.A Higher temperature has two effects: - - More collisions per second, - More energetic collisions. That's why a 10°C rise doubles the rate rather than double temp doubles rate. Conclusion I conclude that the temperature does affect rate of reaction "“ the higher the temperature the faster the rate of reaction. I can see this from my table the lowest temperature has the highest reaction time - 20°C took 57s "“ and the highest temperature has the quickest reaction time - 60°C took 10s. as my graph shows. The line of best fit goes up very steeply. This is because with more heat, the particles of sodium thiosulphate and hydrochloric acid have more energy. This causes them to move around more. Chemical reactions require collisions, and if two sets of particles are moving around quickly there will naturally be more collisions. However, the collisions require the particles to hit each other at a certain velocity, and if this velocity if not reached then the reaction will just not happen. So, at the higher temperatures, more of the particles were travelling at a high enough speed to collide and react. At the lower temperatures it was more difficult for the particles to collide. Particle theory says that for a chemical reaction to occur, there must be a collision at a certain velocity and at a certain angle. Also, the factors that affect the rate of a reaction are the surface area of the solid reactant if there is a solid reactant, the concentration of the aqueous reactant, the presence of catalysts and temperature. In this experiment we were concentrating on temperature, and we were able to draw the conclusion that temperature does, in fact, affect the rate of a reaction, in that when the temperature is higher the reaction takes less time. At 20°C the reaction took a long time to occur. This was because there was not very much heat. Heat provides energy to the particles of reactants, and if there is not very much heat, the particles do not have very much energy. Because they do not have much energy they will not move around much, and will therefore not collide very often. Chemical reactions require a certain speed collision to react, and at this temperature very few of the particles collided, because of not moving around more due to lack of energy, because the heat was not very great. Between 35-55°C the rate of reaction rises very dramatically. I can tell this from my graph, as the line of best fit goes up very steeply. See graph 1.b At 60°c the rate of reaction is at its highest as my graph shows, the best fit line is rising almost vertically. My results and evidence support my prediction very well. They prove the fact that temperature does affect the rate of reaction. I also have the particle theory to support my prediction and conclusion. Evaluation. I believe that the method we used was very good because we had one person using the syringe to mix the liquids together, we had one person timing and one person recording the results and checking the temperatures. I think this was a very good method because it makes the experiment very fair because the results we obtained are more accurate and fair than if we had used a different person each time for each thing. Also, we took great care in making sure that the measurements were as accurate as they could have been. Another reason our results are good is that we took multiple recordings and found the average for them, giving a more accurate result for each temperature. We may have timed one of the results wrong because it was a lot different from the other results, this is called an anomaly and we discarded it as it would have made the average lower than it should be. It is quite difficult to judge properly the exact moment that the cross disappears. It is even more difficult for the higher temperatures, as you would have to have an extremely good reaction time to stop the stopwatch exactly when the cross changes. However, our results were consistent. Although we did have one anomaly we made sure that the results were as accurate as they could have been. Concerning the amount of time taken for the cross to disappear, we could use a different method of working out how long the reaction took to occur. For example, we could shine a torch through the conical flask, and as soon as the light cannot shine through any more, we would stop the stopwatch. This would be one of the things I'd change if I did the experiment again in the future. For further work to our experiment, we could perform the experiment in a vacuum, as then there would be no other factors that can affect our results, other than temperature, which is the variable we wanted.   

My aim is to find out whether temperature has an effect on a rate of the reaction. I am going to be using the example of the reaction between Sodium Thiosulphate and Hydrochloric Acid. Prediction I predict that the higher the temperature, the more quickly the...

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HYPOTHESIS We can recognize four... HYPOTHESIS We can recognize four types of substances due to their structure: ionic, metallic, covalent, and molecular. If a given substance has a metallic luster, is malleable and ductile, is a good conductor of heat and electricity, and has high melting and boiling points, than it is supposed to be a giant metallic structure. If a given substance has low melting and boiling points and does not conduct electricity, it surely is a molecular structure. If a given substance is soluble in water and in other polar solvents, if it conducts electricity after being melted or dissolved, and if it has high melting and boiling points, we can predict that it is a giant ionic structure. So we will have to check which of these properties does a given substance have. APARATUS spatula stirring rod open electric circuit batteries, light bulb, electric wire with two dismantled endings two metal plates the first made of copper, the second made of zinc plastic wash bottle test tubes in amount of 4 watch glasses in amount of 5 Bunsen burner test-tube rack porcelain crucible crucible tongs triangle tripod I decided to use separate watch glass for each substance to avoid possible laboratory errors resulting from contamination with the previous one. CHEMICALS substance A "“ white, granulated powder substance E "“ silver nodules, apparent metallic luster substance C "“ tiny, white crystals substance D "“ a bit larger white crystals substance B "“ black powder distilled water SAFETY RULES Be careful while burning substances in a flame! Don't put your hand into water when the electric current flows "“ you can have your skin seriously damaged! Do not touch hot crucible with bare hand, use crucible tongs! PROCEDURE I put a few grams of each substance except for substance E, which I put into a watch glass using a spatula into separate test tubes, placed in a test tube rack. I put a hint of each substance into separate watch glass. I use open electric circuit in order to investigate electric conductivity of each substance in solid state. I pour a few droplets of water into each watch glass using plastic wash bottle. Then I mix each substance with a stirring rod in order to make process of dissolving faster and more effective. I put two metal plates into each watch glass, so they are partly sunk in the water or solution, if it was formed in the manner one ending of the electric wire sticks to the first plate, and the second ending sticks to the second plate, and it is important that plates do not touch each other. Then I observe whether the light bulb is shining. I take a hint of each substance one by one, using a spatula. I put each substance into a porcelain crucible. I put crucible on a triangle placed on a tripod above the Bunsen burner. Then I turn the burner on and wait up to a minute in order to check whether the melting point is low or high. To handle the crucible I use crucible tongs. Note: I carefully clean spatula before using it again and again, I do the same with the stirring rod and porcelain crucible. DATA COLLECTION A B C D E Conductivity in solid state - + - - + Conductivity after being dissolved - - + - - Solubility in water + - + - - Melting point low high high high high CONCLUSION Substance A is soft and granulated. This substance has low melting point, what indicates that the intermolecular forces are weak. It does not conduct electricity, because molecules are not charged. So substance A has undoubtedly molecular covalent structure. However, on contrary to other substances with molecular covalent structure, it is quite soluble in water, what means that its' molecules can form hydrogen bonds to the water to compensate for the water-water hydrogen bonds broken. Example of such molecules are sugar molecules, so this substance is probably sucrose. In the case of the substance E there is an apparent metallic luster, so it has the giant metallic structure. This metal has high melting point, because it takes a lot of energy to break up a lattice of ions in a sea of electrons with strong forces of attraction, called metallic bonds, between them. Metals are good conductors of electricity because the delocalized, free electrons can move through the lattice carrying charge, when a voltage is applied across the metal structure. The substance C is the only substance aqua solution of which conducts electricity, so it has to have giant ionic structure. It's because the water molecules, which are dipoles, can attract the ions away from the lattice. The ions move freely, surrounded by water molecules. Dissolved or melted ionic compound conducts electricity, because the lattice breaks up and the ions are free to move as charged particles. It can be assumed that substance D is a giant covalent structure, because it is insoluble, it is very hard, but brittle, it forms crystal lattice, and it has high melting point. In addition, this substance does not conduct electricity at all. Substance B is soft and brittle in touch - the sheets can slide over each other easily. It may indicate that this substance has a molecular structure, like the first one. But it has much higher melting point than molecular substances. Besides that, it conducts electricity in solid state, and it does not dissolve in water. This set of properties is very specific "“ it is a combination of single properties of different types of structures. The fact that this substance could well be used as a lubricant layers are easily rubbed off could indicate that this substance can be graphite. EVALUATION After an experiment was finished, our chemistry teacher wrote the names of substances that we were to determine structures of, on the blackboard, so we could verify if our findings were correct and propose improvements to the method in case they were not. And so: substance A appeared to be glucose, substance B "“ graphite, substance C "“ sodium chloride, substance D "“ silicon dioxide, and substance E "“ chromium metal. My predictions according to substance A appeared to be correct. In case of substance E, which is chromium metal, I also obtained correct results. I think that this substance, like it is in case of all metallic substances, has a structure very easy to determine experimentally, even, to say, with bare eye, because we know that metals are the only type of substances that perform a property called metallic luster. Other properties I observed also form a set of properties typical for metal, which is chromium in this case. I was right in case of substance C, which, as it appeared later, is sodium chloride, and sodium chloride is the most characteristic representative of ionic substances. My assumptions relating to substance D are also proved to be correct, since I know now that this substance was silicon dioxide, commonly occurring as quartz, being a good exemplification of properties connected with a giant covalent structure. In case of substance B, I was again right, due to the fact that this substance appeared to be graphite, as I have predicted. Graphite is another example of giant covalent structure, but, on contrary to silicon dioxide, it conducts electricity "“ this property is specific only for this particular substance.   

HYPOTHESIS We can recognize four types of substances due to their structure: ionic, metallic, covalent, and molecular. If a given substance has a metallic luster, is malleable and ductile, is a good conductor of heat and electricity, and has high melting and boiling points, than it is supposed to...

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