This graph shows us that the rate of reaction increases as the concentration increase. The r? value is close to one (0. 9744) therefore our results are quite accurate. The R? value tells us how our results fit the line of best fit, if the r? is one, then our results fit the line of best fit perfectly, making our results very accurate. Method List of apparatus:
Thermometer Method 1. We started off by washing out our buckler flask with an attached delivery tube with distilled water 2. Weighed out 0. 5 grams of marble on a scale. We put a weighing boat on the scale then tarred it; we then used a spatula to put marble powder onto the white dish. We made sure that it was 0. 5 exact, if there was too much we removed some of the marble powder and if there wasnt enough we put more powder in until it was 0. 5 grams. 3.
We made our concentrations (for 0. 5m we put 5 ml of distilled water and 5ml of 1m hydrochloric acid in the 10ml measuring cylinder, for 0. 75m we put 2. 5 ml of distilled water and 7. 5 ml of 1m hydrochloric acid in the 10ml measuring cylinder, for 1. 25m we put 3. 75ml of distilled water and 6. 25ml of hydrochloric acid into the 10ml measuring cylinder, for 1. 5m we put 2. 5ml of distilled water into 7. 5ml of 2m hydrochloric acid into the 10 ml measuring cylinder. ) 4. We put 10ml of a certain concentration into the buckler flask with an attached delivery tube 5. We then filled a bowl with water 6.
We also filled the burette with water and turned it upside down and put it into the bowl of water. 7. We used a clamp to keep the burette in place while we did other things. 8. We put the delivery tube into the burette when it was in the water bowl. 9. We noted down the temperature of the hydrochloric acid in the buckler flask before the reaction. 10. We then put the powdered marble into the buckler flask with an attached delivery tube and put a bung on top of it. 11. We took the temperature of the solution left in the buckler flask after the experiment. We removed the bung when the experiment had been going for 1 minute.
We noted down how much carbon dioxide was produced and washed out our buckler flask with distilled water after the experiment to get rid of contaminates. We noted down the temperature for the reactants because we couldnt keep the temperature constant. Results Concentration (molar) Volume of carbon dioxide produced (cm? ) average amout of carbon dioxide produced Time (seconds)
Rate of reaction (cm? /s) Temperature (°C) 1 2 3 4 5 start of experiment end of experiment applicable anomalous result I got four anomalous results, three of them were very far from the averages and one of them wasnt really very far from the average (I didnt include the anomalies in the calculation of the averages) but it wasnt close enough to the other range of data so I made it an anomaly so that I could repeat the test again and get a better spread of data.
The anomalies could have occurred from either using more than 0. 5 grams of powdered marble or not washing out the buckler flask properly, leaving contaminates to react with the hydrochloric acid, using tap water instead of distilled water to wash out the apparatus or we could have used the wrong concentration in the experiment. This graph shows that there is an increase of carbon dioxide produced when you increase the concentration.
The R? value is better than our preliminary R?value and really close to one (0. 9889) meaning our results are really close to the line of best fit therefore our results are quite accurate because R? value was created to show us how close the results fit the line of best fit by displayed a number from 0-1, 1 meaning that all the results fit the line of best fit and 0 meaning none of the results fit the line of best fit. The rate of reaction increases as the concentration increase.
The R? value is better than our preliminary R?value and really close to one (0. 9889) meaning our results are really close to the line of best fit therefore our results are quite accurate because R? value was created to show us how close the results fit the line of best fit by displayed a number from 0-1, 1 meaning that all the results fit the line of best fit and 0 meaning none of the results fit the line of best fit. Conclusion Overall my results show that concentration increases the rate of reaction.
Concentration increase the rate of reaction because if you increase the concentration of a substance you put more and more of it in a defined space therefore having a lot of reactant molecules in a defined space creating more chances of collisions between two reactants, for example as we increased the concentration of hydrochloric acid, we increased the number of hydrochloric molecules in the buckler flask, allowing more collisions with the marble molecules, therefore creating more products at a quicker rate each time!
Evaluation My experiment went very well, we got some consistent results and our method was quite reliable and accurate. Even though we got some good results, we did have a lot of limitations such as: We couldnt control the temperature of the apparatus because we didnt have facilities that were temperature controlled, so the temperature wasnt kept constant. Even though we couldnt keep the temperature constant, we noted down the temperature of the solution before and after the experiment.
The range on some of the apparatus wasnt very good, we could only see how much carbon dioxide was produced to the nearest 10th of 1 cm? on a burette Due to us trying to keep the surface area constant, we used powdered marble, and because by making marble a powder, the surface area was very great causing a quicker reaction leading on to majority of the carbon dioxide being caught at around 30 seconds or less during the experiment; and little bubbles were let off at a 5 second interval after 30 seconds.
The time when the majority of the bubbles were captured always decreased making the reaction faster each time we increased the concentration. If I could make any improvements to my method and apparatus, I would try and make the range of the Burette better so I could have less chance of making an error when measuring how much carbon dioxide was produced, also I would try to get little particles of marble with the same surface area so that I dont have the majority of the reaction taking place within the first 10-20 seconds or get lower concentrations.
I would also try doing my experiments in a heat controlled room so that the temperature can be kept constant during the day when I do my experiment so my results could be considered reliable. Results: For my preliminaries I only got 1 anomaly but I feel I didnt check the ranges very well because there are parts were the results are 0. 4-0. 5 cm? gap in-between which isnt very good. For my main results I checked if the ranges were very close and they were, I repeated one results to just get a better range because it was 0. 3 cm? apart from the other results.
As you go from one concentration to another you can see that there is a change in terms of how much carbon dioxide is produced. The average amount of carbon dioxide produced goes up by approximately 3-4 cm? as you move up from 0. 25-1. 5 molar. My spread of data for my preliminary work is very bad because the results were too far apart from each other having an effect on the averages so my results wouldnt be considered very accurate and reliable, if you look at my preliminary graphs my first two points of data are far off the line of best fit unlike the other points which nearly fit the line of best fit .
But my main results spread of data is very good, with me repeating one of my results just to get a better spread of data with the majority of my results fitting the line of best fit. I feel my results are quite reliable because I repeated my experiment when I got anomalous results, I repeated my experiment three times also I got a good spread of results for my main results, but my results could be considered unreliable and inaccurate due to no care taken on my preliminaries because I didnt make sure the range of my results was very good and my average result for 0.25 m is nearly 10cm? less than my average results for 0. 50m, meaning something wrong happened because all the other results are 3-4 cm? apart.
Conclusion: I can make the right conclusion for my results because the range of results and spread of data for my main results are quite good, my results are also quite reliable because I repeated them 3 times and even repeated my experiment when I got anomalies, the fact I got anomalies ruins the chances of my results being very good because by getting anomalies my method has flaws in it.
There thing preventing me from getting a totally good conclusion are the anomalies because some of them are out of the range of the data and also I didnt take my preliminaries as serious as my main results resulting in an odd string of results for 0. 25 molar which doesnt fit the pattern of my other results.
Bibliography: http://en. wikipedia. org/wiki/Collision_theory http://www. chemguide. co. uk/physical/basicrates/catalyst. html http://www. chemguide. co. uk/physical/basicrates/introduction. html http://www. webchem. net/notes/how_far/kinetics/rate_factors. htm OCR Twenty first century science GCSE Chemistry.