I have chosen to do 5 experiments to see what will happen when you keep the temperature the same but change the concentration, each of the experiments will be taken over a 4 minute period, jotting down the amount of Carbon dioxide which is being given of every half minute.
This action takes place when the Calcium Carbonate (CaCO3) touches the Hydrochloric acid (2HCL) the molecules then start reacting with the Calcium Carbonate (CaCO3)
Preliminary experiments
We first before we did the experiment had to decide on how much concentration we would be using i.e. 90,100,110,120ml I then asked myself what temperatures would give me the greatest range of results, I thought that room temperature and at 50° would be good enough. Because if you go any higher than 70° the Hydrochloric acid will start to evaporate and would not be a fair test.
Also time was a crucial thing because we did not have enough time to do 10, 15, 20 minutes, so I thought that a reasonable range of results would be around about 4 minutes, marking it down every half minute.
Obtaining evidence
During our experiment I made sure that I was working safely enough, for example: I wore my goggles at all times, I made sure that I was not running about, I made sure that I did not spill any Hydrochloric acid onto the floor. I collected a variable amount of results, in which will help me be able to produce a graph at the end, I have recorded my results in the table below:
These results were at room temperature the next ones are at 50°c:
As I predicted the hotter temperature is the faster reaction will be, because when the molecules in side the Hydrochloric acid are heated they gain more energy than the molecules that are at room temperature, when this happens then the molecules will have a great chance of colliding with each other, when this process happens the reaction will speed up. I think that one of our results were wrong because the hydrochloric acid stops producing Carbon dioxide and normally it will not do that.
Here is the result that was wrong and also the repeated results:
Repeated results:
These repeated results are better because there is a following pattern of how much Carbon dioxide is being produced, instead of the Carbon dioxide starting and stopping.
My results are not that reliable because I did not have enough time to extend the amount of time given to make my results more accurate.
If I had the time I would have gone for 10 or 15 minutes this would have given me a greater range of results to prove that when you heat the hydrochloric acid the reaction is faster and you will get greater results to draw from.
There are many problems with the experiment, the first is the Calcium carbonate, you might have think you have got 1g of Calcium carbonate but the surface area might be bigger, with this problem the reaction could happen faster and slower because that surface that is face up is the first thing that the molecules hit and if this is bigger or smaller then there will be slight difference in the speed of the reaction. The second one is the temperature of the (2HCL) Hydrochloric acid, this occurs when you add the cap on top of the beaker with the pressure you have to put the cap in to make it a tight seal you release some of the heat (also when you put the cap on top, when you force the cap down you force air into the measuring cylinder which could start you of wrong for measuring the amount of CO2 is given of . so in the long term my results are not that terribly accurate because of the previous aspects.
Analysing and considering Evidence
I have found out that when you heat Hydrochloric acid to a temperature you will get a faster reaction and more Carbon dioxide is given of, this is done by when you heat the Hydrochloric acid up the molecules gain more energy, then the molecules are like a (bull in a china shop) they fizz about a lot, this then causes the molecules to collide with each other making the reaction happen quicker.
From my results I can see that when I heat up the Hydrochloric acid (2HCL) the amount of CO2 given of is greater, also wiliest heating the solution up changing the concentration from 0.25m to 2m should help me to get better results and how much difference there is between room temperature and having the Hydrochloric Acid (2HCL) at 50°C
I have proved my prediction because I said that when I heat the solution (CaCO3 +2HCL) up to a temperature that is greater than room temperature then the molecules that are inside will gain more energy and have greater chance of colliding, as soon as the collisions happen then the reaction happens faster,
Evaluating
We conducted a experiment to see what the difference was between having the Hydrochloric acid (2HCL) at room temperature and having it at 50°C and into each solution I added 1g of Calcium carbonate we then timed the rate of reaction for each temperature and recorded our results. I expected the hotter Hydrochloric acid (2HCL) would be faster because the molecules within the solution will gain more energy from the heat and therefore causing the molecules to have a greater chance of colliding at a faster rate to cause the reaction
Here is the results that were wrong, I think that the problem with these results is that the surface area is varied, as you see in the first results you can see that the amount of CO2 that is given of a measured is that it stays at the same measurement for 1 minute, this means that the surface area of the CaCO3 was reasonable small for the reaction to take place, but if you look at the second recorded results you can see a dramatic change, the amount of CO2 is a constant pattern, there is no stoppages and stalls, this means that the surface area of the CaCO3 this time was a fair size, this allowed the reaction to happen how it should.
Repeated results:
If I had the time I would have gone for 10 or 15 minutes this would have given me a greater range of results to prove that when you heat the hydrochloric acid the reaction is faster and you will get greater results to draw from.
Also there is a possibility (if allowed) I could have had more concentrations of (2HCL) Hydrochloric acid this would have given me greater results to comment on.
I could of used a higher temperature of Hydrochloric acid (2HCL), but the problem with this is that if you heat the hydrochloric acid (2HCL) to high you start to evaporate the solution, as soon as you do this the experiment becomes a un fair experiment.
I could of be sure of my results because I had a fair idea that as soon as you heat the Hydrochloric acid (2HCL) to a temperature that was hotter than room temperature you were always going to get these kind of results to start with, the first experiment I thought was wrong because the amount of gas given of was stopping and starting producing CO2, the answer to this could have been that the surface area of the Calcium carbonate could have been smaller or bigger for the molecules to collide with the Calcium Carbonate.
To make sure that my conclusion was right I could have done the experiment again and tested my theory of molecules colliding to make the reaction happen faster.
Theory used to predict the rates of chemical reactions, particularly for gases. The collision theory is based on the assumption that for a reaction to occur it is necessary for the reacting species (atoms or molecules) to come together or collide with one another. Not all collisions, however, bring about chemical change. A collision will be effective in producing chemical change only if the species brought together possess a certain minimum value of internal energy, equal to the activation energy of the reaction. Furthermore, the colliding species must be oriented in a manner favourable to the necessary rearrangement of atoms and electrons. Thus, according to the collision theory, the rate at which a chemical reaction proceeds is equal to the frequency of effective collisions.
I could have also changed the amount of 2HCL that I used to prove that when you heat the Hydrochloric acid (2HCL) and use however much concentration you use that as soon as you heat it up you will always get better results in the end.
