Hydrochloric acid and magnesium Essay Example for Free

Hydrochloric acid and magnesium Essay The temperature raised considerably on the other 4 due to the quickness of the reaction. This heat would quicken the reaction due to the fact that the molecules would be vibrating and therefore colliding more often (as explained before).   Sometimes the magnesium floated on the top of the acid. This was not a problem in most cases because the bubbles over lapped the magnesium so it also reacted from the top. However, due to the 0. 5 mole slow reaction, this did not happen. Because of all these inconsistencies, it is difficult to say how reliable my results are. I think that because the results are what I expected, and because I carried out the experiment with care, also the fact that I repeated the experiment many times makes it highly unlikely that the results are inaccurate enough to not be able to draw a valid conclusion from. Evaluation This was a good experiment because it clearly showed my prediction, and where it didnt I was able to spot the errors and am now able to make the experiment better. I worked as I kept a fairly high degree of accuracy, and the experiment had a high margin of error, due to the length of time some of the results could to take. My results were fairly accurate but my error in the rate of reaction of the 0. 5 mole acid could have been down to accuracy, but I seriously doubt it, as I asked around to see if other people had encountered the same problem. Everybody had. I have several theories of why the 0. 5 mole acid did not react as expected.   The temperature raised considerably on the other 4 due to the quickness of the reaction. This heat would quicken the reaction due to the fact that the molecules would be vibrating and therefore colliding more often.   Sometimes the magnesium floated on the top of the acid. This was not a problem in most cases because the bubbles over lapped the magnesium so it also reacted from the top. However, due to the 0. 5 mole slow reaction, this did not happen. To make my experiment more accurate I could have Weighing the magnesium instead of just measuring the length of it. This was an obvious problem as I think my spread of results for the end amount of hydrogen given off was too high. I would have preferred if it were only 1 or 2 ml. But it was 4. 33ml   Setting up another system for getting the magnesium into the acid. When I did the experiment I just dropped the acid in and attached the gas syringe as quickly as possible. The disadvantages with this were:   It was inaccurate   The start of the reaction would be when most gas was given off. The time of attaching the gas syringe was always different.   The gas syringe often jumped forward slightly when I put it on.   Repeated the experiment more times.   Used more acid. This would shop the temperature problem as the temperature would be less likely to change, due to the increase in energy it would take to heat the water. Because of all these inconsistencies, including the 0.5 mole acid result, it is difficult to say how reliable my results are. They are not accurate enough to study the experiment in-depth, however for a general hypothesis such as Aiming to find out whether the concentration of acid effects the speed at which gas is given off, between hydrochloric acid magnesium ribbon and because the results are what I expected, and I carried out the experiment with care, also the fact that I repeated the experiment many times, it is reasonable to presume that I can draw a simple conclusion like, the higher the concentration, the quicker the gas will be given off. If I were to do the experiment again I would change the way I inserted the magnesium into the flask. I think I would have a double chambered flask that would be able to have the wall removed. See diagram. I could combine this idea with the alternative way I could do the experiment, as described in my planning. The method would be to: Place magnesium and the acid in a flask, which is then plugged with cotton wool, to prevent any liquid splashing out, during the reaction. Next, the flask is weighed, then tipped up to let the reactants mix and a clock is started. The mass is noted at regular intervals, until the reaction is complete. I would use the same volumes for all the chemicals in the new experiment, as I see no good reason changing them. I would expect the graph for the result to be much the same, but obviously with different axis labels and values. For example In conclusion, the experiment did prove my prediction that the rate of reaction doubles with when the acid strength doubles. Daniel Hill 10S Rate of Reaction Between. doc Page 1 of 8 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.