The aim of the experiment is to find out the effect of concentration of acid, in the reaction between dilute Hydrochloric Acid and the Magnesium Ribbon.
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INVESTIGATING THE REACTION BETWEEN MAGNESIUM (Mg) AND HYDROCHLORIC ACID (HCL) AIM! The aim of the experiment is to find out the effect of concentration of acid, in the reaction between dilute Hydrochloric Acid and the Magnesium Ribbon. Depending on how fast the reaction takes place, indicates the rate of the chemical reaction, (how often the molecules collide). In the investigation I will test the different concentrations of acid reacting with the magnesium ribbon. PREDICTION! I predict that as the concentration of the hydrochloric acid decreases (becomes more diluted), the time taken for the magnesium ribbon to dissolve will increase. I also predict that as the concentration of the hydrochloric acid decreases, the rate of reaction will double. BACKGROUND KNOWLEDGE! The background knowledge is very important because it can give us an inkling as to what we think can happen in the experiment, and from using the background knowledge I can make a prediction, and then justify it. I know that there are certain aspects of the experiment that can change the course of the results. One of the factors is the 'Collision Theory'. The Collision Theory describes how the rate of the reaction will decrease as the concentration of Hydrochloric Acid decreases. The rate of the reaction is the time taken for the Magnesium Ribbon to dissolve when it reacts with the Hydrochloric Acid. The Collision Theory states that the more concentrated the reactants are, the greater chance there will be of a collision between the two particles and the reaction will happen faster. As the reaction continues, the concentration of the reacting substances will decrease (the Hydrochloric Acid)
PRELIMENARY RESULTS! This is the preliminary table of results: VOL OF HCL (CM3) VOLUME OF H20 (CM3) CONC MOLAR TIME 1 (S) TIME 2 (S) AVERAGE TIME (S) RATE 1/T 10 0 1 11.01 9.06 15.54 8 2 0.8 22.60 22.34 33.77 6 4 0.6 64.45 63.12 96.01 4 6 0.4 120.34 195.56 218.12 As the results show, as the concentration of the Hydrochloric Acid is diluted, the slower the rates of reaction are. I predicted that the rates of reaction would decrease and they have, as looking at the average results, at a concentration of 10cm3 Hydrochloric Acid, the rate of reaction is timed at 15.54 seconds, whilst at a concentration of 4cm3 the rate of reaction is 218.12 seconds, so for the preliminary results, my prediction was correct. ANALYSIS! This is the final table of results: VOL OF HCL (CM3) VOLUME OF H20 (CM3) CONC MOLAR TIME 1 (S) TIME 2 (S) AVERAGE TIME (S) RATE 1/T 10 0 1 11.02 10.05 16.045 8 2 0.8 23.00 24.20 35.10 6 4 0.6 63.23 61.48 93.97 4 6 0.4 125.68 131.32 191.34 2 8 0.2 202.34 197.28 300.98 The above table is the final table of results, and the results show that part of my prediction was correct. I correctly predicted that as the concentration of the Hydrochloric Acid decreased, the rate of reaction would increase. The first record states that it took 11.02 seconds for the Magnesium Ribbon to dissolve in a solution that had 10cm3 of Hydrochloric Acid. At a volume of 8cm3 the rate of reaction increases to 23.00 seconds, which is an increase of 11.98 seconds.
Another reason is that I cut the length of the Magnesium too big at a concentration of 6:4 and too small at a concentration of 2:8. Another explanation is that there could have been a change in temperature. Although it is not a very strong explanation, it is still a theory. And my last theory as to why I obtained the anomalous results is that when the reaction takes place bubbles of H2 are given off which might stay around the Magnesium which therefore reduces the surface area of the Magnesium and so the Hydrochloric Acid cannot react properly so this effects the results. If I were to do the experiment again, I would like to have more time so I could get more results and get a bigger variety of knowledge from the results. If I was to repeat the experiment my second aim, would be to eradicate any anomalous results, so if I added too much or too little Hydrochloric Acid or too much or too little Water, I would have all the measurements poured out before in separate containers. That would rule the risk out of me obtaining anomalous results due to too much or too little of a substance. To eradicate the risk of the Magnesium Ribbon being too big or small, if I was to do five experiments, I would get 5 pieces of Magnesium Ribbon and put the pieces one under the other, measure the Magnesium Ribbon on top, and then cut down the five Ribbons, therefore, even if the Magnesium Ribbons have been cut too small or big, they would all be exactly the same size.
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