The effects of concentration on reaction rates Essay Example for Free

The effects of concentration on reaction rates Essay I could back this conclusion up by doing two things. Firstly, I could use my average time graph (graph 1) to work out what time any concentration would take to complete its reaction. This is especially because of the fact that all my results I tested followed a trend. What I can do is to look where any concentration level is in line with the line of best fit, and then I could take this point on the line of best fit and look to see where that point lines up with the time taken. An example is on the next page: Here you can see that the point indicated as the intersecting point is where the concentration levels and time taken axis meet on the line of best fit. This is exactly how I could prove my conclusion correct, by taking any concentration, and then test the concentration in the same way as in my method to see if the time taken follows this pattern. If it does, then I could easily prove my conclusion to be correct. Evaluation: The times would have been very unlikely to be the same, particularly under the conditions of the fact that we had a strict time limit of two lessons, including getting the equipment out and clearing it up again. Overall, this was a very tight deadline to meet, and I eventually realised I needed to try and run my first and second tests simultaneously in the second lesson, as I was nearly out of time. This rush could easily have affected my final results in several ways, all because of the rush I was in to get all my results. The magnesium floating in the HCl may have been a problem too. I dont think it would have affected the results much, but because it was floating, not all of the magnesium was in the acid at the same time throughout the reaction, and therefore this may have meant the reaction took longer as it couldnt react with all of the magnesium straight away. I could have got over this by poking the Mg down, but that may have affected the results as well. If I were to use a substance that would react with the HCl in ANY way (even if it would be unnoticeable to the naked eye), then the reaction rates would have probably slowed down, because some of the HCl would have reacted with the other substance, leaving less of it to react with the Mg. The other (more obvious) point is that I would have found it hard to poke three pieces of Mg in different test tubes down at once. The other way which I could have solved this, would be to make the density of the Mg larger, so that the Mg would sink naturally to the bottom of the test tube. This could have been done either by redoing the tests with more magnesium (a longer strip), or by using less HCl. I would have done this, but the tight time limit meant that I couldnt redo all the tests that I have already done in time, before realising this. Another way my results could have been affected is that because the 0. 1 reading took a long time to complete, meaning that I may not have noticed that the reaction had finished straight away. I dont think this happened, though, so Im not too worried about this. Finally, and this occurred in my second test which could indeed explain my ringed faulty result, I admit, time got the better of me and so I didnt wash out my measuring cylinder out after measuring each concentration of acid. I may have measured smaller concentrations first and these concentrations could have mixed with the one I was using then to not give the mole that I said I was using for this test. To get over this problem, I could either have rinsed out the cylinder before measuring each concentration, or even by sharing cylinders with other people, of which each cylinder would only be used for one concentration. Overall, despite these problems, I dont think I will have made a bad attempt at the experiment, because the results were similar both times and they did follow a trend on my two graphs. 1 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section. Download this essay Print Save Heres what a teacher thought of this essay 3 star(s).