This Sc1 is about looking at what affects the rate of reaction in an experiment and why it affects it. For example you can use several ways to find this out.
One way is by adding a catalyst, by adding a catalyst you can increase rate without the catalyst being used up itself. Different reactions need different catalysts. They also can reduce the activation energy, this is good for big industries because the faster the product is made the less costly it will be. Activation energy basically means the energy needed to break reactant bonds.An example of a catalyst being used is, magnesium dioxide catalysing the decomposition of hydrogen peroxide. Another to see what affects the rate of reaction is to increase the temperature. By increasing the temperature, the particles will have more energy and will move faster.
This will make them collide more and with greater energy. Changing the surface area affects the reaction as well. A larger surface area will give a faster reaction. This is because reactions happen on surface of solid reactions. An alternative is to increase the concentration of one of the reactants, e.g.
when acids an involved you could increase the strength of it.This will equal more reactant particles in a certain volume so more chances of collisions. There is one last way that I found out from a science book, you could change the gas pressure. When reactants involve gases a higher pressure gives a faster rate. This is because pressure pushes particles together and there is more chance of collision.My group and me decided to do the change of the concentration because we think it would be better and we would see clear differences. We have to observe the time and gas given off and get as much results as possible. The reactants we are using are nitric acid (2HNO3) and calcium carbonate (Marble and Limestone CaC03).
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Our reaction can be written as:Calcium Carbonate + Nitric acid Calcium Nitrate + Water + CarbonDioxideCaCo2 + 2HNO3 Ca (NO3) + H2O + COPrediction/HypothesesI think that changing the concentration of the acid will speed up the reaction because the more concentrated the acid is the more particles in a certain volume, so more chances of collision. I think this will give a faster rate.MethodIn this experiment I used a lot of equipment, which includes a conical flask, Bunsen burner, test tubes, basin, delivery tube, beaker, timer, calcium carbonate, nitric acid and water. First we had got all the equipment and set it up. We filled the basin with water till about 3/4 of the way. Then we put the test tubes into the basin and got rid of all the bubbles by letting all the air out. Next we measured out a 2grams amount of marble (calcium carbonate) chips and placed them into the conical flask.
Before attaching the delivery tube to the conical flask we put in 60mls of nitric acid at a concentration of 0.5 molar. We had to dilute the acid because the smallest strength we could get was 1 molar.Putting 30mls of water and 30mls of acid rather than 60mls of acid did this. There was no reason for 60mls of acid just it made it easier to dilute and measure. After the acid was put in we attached the delivery tube that was under the test tube in the basin. We did this because we were measuring gas that was being given off.
We read the amount of gas being given off the side of the test tube, which had numbers going up to 10 down the side. Each time the tube had ran out of water we changed it to another tube, which was already in the basin and added the reading from the previous tube. Each time we did the experiment we timed the reaction for five minutes. We gradually increased the concentration of the acid by 0.5 molars.The most we increased it till was 2 molar because this was the most concentrated we could get hold of and we never needed anymore to see the result. To make it a fair experiment we had to measure the acid and water as precise as possible each time round. Also we had to make sure that when we changed between test tubes we tried not to lose any bubbles.
The time was stopped and started as close as possible without too much of a difference. We tried to as much as possible to get everything thing on target, but there were some slight mess-ups. Every molar was repeated 3 times for accurate results in case we had accidentally got something wrong in one.
DiagramResultsThese are our results for each different molar of concentrated acid starting from 0.5 to 2.0 molar.
Each one was repeated three times for accurate results.Time (sec)1st2nd3rdAverage00000300000600.50.50.20.4900.70.
80.50.71201.01.
20.811501.61.
51.01.31801.92.01.51.82102.
52.72.02.42403.03.
52.432703.84.22.93.63004.
65.23.74.50.5 MolarTime (sec)1st2nd3rdAverage00000300.20.
20.30.2601.
21.21.41.
3902.52.72.42.51204.25.
23.94.41506.29.16.37.
21809.410.39.59.721011.714.512.112.
824015.216.014.915.427017.
818.617.718.03002020.820.420.
41.0 MolarTime (sec)1st2nd3rdAverage00000303.51.
11.21.9608.73.23.65.29013.
77.27.69.512019.013.012.
814.915023.418.
317.019.618028.023.119.223.421032.
327.726.528.824035.332.230.532.727038.
737.635.537.330042.741.
239.541.11.5 MolarTime (sec)1st2nd3rdAverage000003023.
21.82.3606.89.56.57.69014.
018.312.815.012023.026.022.323.815028.
037.025.630.218036.338.730.635.
221042.443.038.041.124041.349.
045.745.327054.255.351.653.730057.562.
054.958.12.0 MolarAnomalous =GraphConclusionAfter doing this is experiment and getting as much results as possible I have found out that increasing the concentration of the acid does affect the rate of reaction. Each time we had increased the concentration of the acid the results went up in the amount of gas given off. This means the rate was faster and it had speed the reaction up. My results showed that more increase equalled more gas given off.
This went really well with my prediction because I had said that the more we increased the concentration, the rate of reaction would be increased as well. As I said in my prediction this is because there were more particles in a certain volume of acid so there were more collisions. My results fit my prediction quite well, the amount of gas does increase as we increase the concentration, but there are one or two anomalous results.EvaluationI think our experiment went really well and I think we made as precise as possible. Even though we never had all the high tech equipment we still made use of what we had.
Our results were really good because they were very close to what we thought would happen. We had repeated the experiment three times and each time we did it they were nearly the same, so we knew we weren’t going wrong. There were some anomalous results, which were a little off. These could have come up as a result of wrong a reactant or wrong timing of something.There were one or two major times where all the results of that experiment were different to the others, this was the first experiment of the 1.5 molar-concentrated acid.
This could have happened because the acid was measured wrong; all the results for that first experiment were higher than the others. This also could have been a result of too less calcium carbonate being put in, which resulted in a quicker reaction. We knew this column was odd because the other results for that 1.5 molar experiment were similar too each other. Other than that the majority of the results were all overall quite good.The experiment could have been improved a lot and we could have got much more accurate results. We could have improved it by using accurate scales, which would have told us more precise readings.
Another way to improve our experiment is to use a gas syringe; this would have made it easier to read the reading when the gas was being given off. Other things we could have done are to use better measuring instruments for the acid. By using these two improvements we could have got better results and overall much clearer difference.
