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SCIENCE COURSEWORK: RESISTANCE OF WIRE EXPERIMENT
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Risk Assessment To keep the experiment safe I shall keep electrical conductors away from the plug sockets. I will take care not to hurt myself or anybody else with the crocodile clips. I will also not turn the power socket on full so as that the wire does not burn or set fire to any surrounding objects or burn anybody. Preliminary work Firstly I assembled the apparatus as shown in the diagram below. For the wire I used 34 standard wire gauge wire. I then took measurements placed the two wire ends marked with an X...
Voltmeter reading by the Ammeter reading, giving me the resistance. This experiment would then be repeated three times so as to determine any anomalous results.

Diagram of apparatus for alternative experiment

I predict that the readings on the Voltmeter and Ammeter would be higher but when divided and the resistance worked out that the resistance would be very similar to that of the results worked out in my main experiment. This would be a useful experiment to carry out alongside my other to support my theory and satisfy my aim.

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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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Mankind has always been fascinated with...Mankind has always been fascinated with the thought of what everything is made of. The answer can be found in the periodic table but that hasn't always been the case"¦"¦"¦ Once upon a time in a kingdom far, far away live a Greek scientist called Aristotle shown right. Around 300BC he declared that every thing is made up of only four elements. These were fire, air, water and earth and that all matter is made up of four elements. Also that matter had four properties, hot, cold, dry and wet. But this did not satisfy ever one and so the next person to challenged this idea was the idea of Hennig Brand. Brand was the first person to discover a new element. He was a bankrupt German merchant who was trying to discover the Philosopher"s Stone which was supposed to turn inexpensive metals into gold. He experimented with distilling human urine until in 1669 he finally made a glowing white substance which he named phosphorus. He kept his discovery secret, until 1680 when Robert Boyle rediscovered it and it became public. Then later in 1789 Antoine-Laurent de Lavoisier shown here released his Traité Élémentaire de Chimie it was thought to be the first chemical text book. It contained a list of elements, or substances that could not be broken down further, which included oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and sulphur and a further 26 what he thought to be elements. While many leading chemists of the time refused to believe Lavoisier"s new revelations, the Elementary Treatise was written well enough to convince the younger generation. This model only classified elements into metals and non-metals and so was not accepted. The next knight in shining armour to continue the periodic table legassy was Jons Jakob Berzelius who introduce a table of atomic weights. In his weights, he used oxygen as a standard, setting its weight equal to exactly 100. He also measured the weights of 43 elements. This paved the way for the German chemist Johann Dobereiner right. In the 1820s Döbereiner noticed an interesting pattern in some sets of three similar elements. He noticed that the atomic mass lay roughly halfway between the lightest and heaviest ele ments in the group of three. He called this group the triads. Then many elements had not yet been discovered and some substances were thought of as elements that were actually compounds. So it"s not surprising that Döbereiner could only find a few triads. Certain triads were calcium, strontium & barium and chlorine, bromine & iodine. Then came along the British chemist John Newlands. In 1864 he suggested that if the elements are put in order of atomic mass, every eighth element was similar. He called this his Law of Octaves. This pattern only worked for the first 15 or so elements known at that time. Fellow scientists at the time were not very impressed. Some big bad wolves even said that he might have had better luck putting the elements in alphabetical order. It was a few years later that the real breakthrough came. A Russian chemist called Dmitri Mendeleev shown hard at work was also struggling to find any underlying pattern in the chemistry of the elements. This knight in shining armor also thought that the key was to arrange the elements in order of atomic mass. But try as he might he didn't know why the pattern kept breaking down. He spent about 13 years gathering data on the problem and eventually solved it by deciding to leave gaps so that similar elements could always line up in vertical columns. Mendeleev enjoyed playing card game patience so he made a card for each element. This helped him working out his solution as he made lines of similar elements, one on top of another. Eventually he published what he called his " Periodic Table'. At the time, many scientists doubted Mendeleev"s theory because he left gaps and changed the order of elements to make his table work properly. However, he won them over by predicting the properties of elements that were as yet undiscovered from the patterns evident in his table. When the element germanium was discovered in 1886, it closely matched the properties Mendeleev had predicted using his Periodic Table. The science community of that time was dumbstruck at that Russian scientist and his new table, and today people still think it an extremely groovy piece of science. Mendeleev's table stood strong until the beginning of the 20th Century. The discovery of atomic properties led to the quantum theory which was a clever piece of science only understood by three or four magic wizards on this planet. The periodic table of the elements was reorganized to accommodate this new theory, made to look like how we know it today. The original sorting organized by Mendeleev was dropped in favor of the more logical sorting according to the atomic number and the groups were arranged according to their electronic configuration. *Even now the periodic table of the elements as we know it is not complete and every now and again a knight steps forth and takes on the legacy of his fore fathers and a new element is synthesized and added to Periodic table. And so the Periodic table was used for ever more and that is why its founders will live happily ever after.   

Mankind has always been fascinated with the thought of what everything is made of. The answer can be found in the periodic table but that hasn't always been the case……… Once upon a time in a kingdom far, far away live a Greek scientist called Aristotle shown right. Around 300BC...

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The aim of this experiment is...The aim of this experiment is to find out if the resistance of a piece of wire will change if we vary the length. To do this I will set up a circuit that will include an ammeter, a voltmeter and a piece of wire. The wire will be a different length each time. I think that there will be more resistance on a longer piece of wire "“ the longer the wire, the higher the resistance. This will happen because of the amount of particles inside the wire that the flow of electrons will need to pass. In turn, there will be more collisions between the electrons and the atoms inside the wire. This is the resistance. A higher resistance will mean more collisions. To succeed, I will need to keep the temperature below a certain level as if the wire gets too hot, the atoms inside the wire will begin to move more and this would affect the resistance. I also need to be sure to use the same thickness and type of wire each time. If the wire was thicker on one measurement, there will be more atoms that the negative electrons would collide with. The wire I will use is Constantine 0.31mm wire. My preliminary work shows which voltages to use without the wire getting hot. Length cm Voltage V 10 0.25 20 0.35 30 0.42 40 0.71 50 0.96 60 1 These voltages prevent the wire from heating up, so all I need to do is keep the voltage below 1V each time. I need to keep all of these the same to be sure of obtaining a reliable set of results, and a fair test. I am deliberately changing the length of the wire and the voltage to prevent the wire from heating. I decided to use six different values, from 10-60cm long wires. I think this is better as the difference between the highest and lowest is high. If the values had smaller differences, a mistake of 1mm in the measurement could make a huge difference, but it would not make as much difference in the values I am using. To make sure the results are reliable, I will repeat the experiment and work out an average between the two results I have. This is in case of an inaccurate result. Length cm Current A Voltage V Resistance ? Average ? 1 2 1 2 10 0.37 0.33 0.25 0.694 0.714 0.704 20 0.26 0.26 0.35 1.346 1.346 1.346 30 0.22 0.22 0.42 1.909 1.909 1.909 40 0.28 0.28 0.71 2.536 2.536 2.536 50 0.3 0.3 0.96 3.2 3.2 3.2 60 0.26 0.27 1 3.846 3.704 3.775 First of all, the resistance did increase as we increased the length of the wire. The results are almost on a straight line, so it seems that the resistance is directly proportional to the length of the wire. If the length is doubled, the resistance also doubles. The line of best fit does not go through the origin. It would be thought that no wire would have no resistance, but the crocodile clips and the connections would also have a resistance. Every point lies almost exactly on the line of best fit, except the 30cm measurement, although it is only around 0.5? from it. My original hypothesis was correct "“ the resistance increased with the length of the wire. This happened because of the amount of particles inside the wire that the flow of electrons will need to pass. In turn, there will be more collisions between the electrons and the atoms inside the wire. This is the resistance, and a higher resistance will mean more collisions between the free electrons in the current and the atoms inside the Constantine wire. The results are accurate, as I used very small measurements cm/mm and left my results at two decimal places. If I had, for instance, used inches and rounded all of the results to one or no decimal places, the results would be far less precise. I can also tell that they are reliable as the graph makes an almost exact straight line. Had the results been all over the graph with a line of best fit far away from the points, I could not say this. I am very confident that my conclusion is right. This is because of the fact that the points lie on a straight line that is directly proportional to the y-axis. If the length is doubled, the resistance also doubles. To improve the reliability, I could repeat the experiment more than just once. If I had an average of three or four tests, I would have a far more accurate graph. Resistance is measured in ohms.   

The aim of this experiment is to find out if the resistance of a piece of wire will change if we vary the length. To do this I will set up a circuit that will include an ammeter, a voltmeter and a piece of wire. The wire will be a...

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