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    hmmmmmmmmmmmmmmm i did this coursework a very long time ago mate. thanx neway

    for the secondary sources you'll need to annotate it, you cant just hand sources without them being annotated on and get them from at least 3 different sources i.e. internet, text books, magazines

    consider things such as the surface area i.e the smaller the granules of the sodium carb, the more surface area they'll have and the faster rate

    variables: catalyst , concentration and energy supplied which comes from the temperature, the higher the temperature, the more ke it has and hence more collisions can occur ALSO show what you mean by a catalyst and do say that it speeds up a raction WIHTOUT getting used up
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    (Original post by shafi)
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    HERE IT 'S






    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
    hi i am also doing this experiment for my A-level coursework. what exactly is the Maxwell-Boltzmann curve? would i find that in a text book? it doesn't sound like its going to be detailed enough for A-level but i guess if u do more than 1 experiment it should be ok! thank u for ur info given..anyone got any more??? pls thanx i am struggling here!!!
 
 
 

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