Dilute hydrochloric acid+ calcium carbonate calcium chloride + carbon dioxide + water. 2HCl(aq) + CaCO3(s) CaCl2(aq) + CO2(g) + H2O(l) Diagram of equipment: I will use a gas syringe to measure the amount of gas given off, a conical flask to hold the reactants, a measuring cylinder to measure the acid, a set of scales to measure the marble chips and a clamp stand to hold the gas syringe. I will also have a rubber tube and bung to transport the gas into the syringe. Results of Rates of Reaction Experiments: Throughout the experiments, I used 2 molar hydrochloric acid and 1gram of medium sized marble chips.
This was to keep the tests fair. I varied the concentration of he hydrochloric acid by combining different amounts of water with different amounts of hydrochloric acid to decrease the molarity but keep the same amount of liquid in the equation. 10ml acid with 0ml water Time 1st result 2nd result 3rd result with 2ml water Time 1st result 2nd result 3rd result rd result ml acid with 5ml water Time 1st result 2nd result 3rd result 3ml acid with 7ml water Time 1st result 2nd result 3rd result 20 4 2 No result Averages of each concentration.
Time Conclusion:From analysis of the results I have recorded, I have come to the conclusion that the rate of reaction gets slower when the concentration of acid is weakened. This is proven by the graphs showing my data. This proves my prediction about the particle theory. I stated that when concentration was increased, the rate of reaction increased because the amount of particles increases but the surface area stays the same so the particles are closer together and therefore have more collisions. Evaluation: the experiment I carried out went according to plan but the results I obtained weren’t what was predicted or expected.
I have obtained sufficient amounts of results but it still doesn’t help me come to a conclusion. I feel that I controlled the experiment well but I don’t quite understand why the results turned out like they did. The only resemblance I can see between the results is that all the results travel upwards except for the averaged results for 90%. looking at the averaged results, the results are quite ‘jumbled up’ because 30% is higher than 50% and 90% and 70% are higher than 100%. From these results, it is unclear to see whether or not the rates of reaction changes when concentration is changed.
The experiments were very suitable to test whether concentration changes the time taken for a reaction to occur between calcium carbonate and hydrochloric acid. The results given were hard to decipher because some reactions were quicker than others and lasted longer than others but that was because I used the averaged results to make the averaged results to make the graph of all results. I think that when I averaged the results, there was one or two anomalies singly which changed the average for each result. This also altered the 90% result because it was impossible for the results to go down but they did at 90%.
I chose a sufficient range of variables to test because I don’t think it was necessary to do any variables less that 30% because it would have been extremely slow with not much reaction taking place and that is evident from the other results. The results for 50%, 80% and 100% were anomalous because 100% was below 90% and 70% while 50% was the lowest result, lower than 30% and also, 80% was lower than 80%. But it could also be seen as 30%, 70%, and 100% being anomalous because 30% is higher than 50%, 70% is higher than 80% and 100% and 100% is lower than 70% and 90%.
So in comparison to reach a final result, it is impossible to define which result/results were anomalous except I came to the conclusion that 100% is anomalous. Looking back on when I performed the experiments, I have realised that I obtained the results of each variable on different days so I came to the conclusion that we may have used different equipment each day which caused the range in results. I am quite sure that it was the gas syringe that was faulty but that is the only reasonable explanation I can think of.
I received plenty of results to come to a conclusion and if I could do it again, I would do more variables and test each variable one or two more times so that I can pick out the best three for each variable. That would give me a more consistent result. Leah Rohlf-Baldock GCSE Science Coursework Rates of Reaction 07/12/2007 Page 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.