Variable/s: the ideas I came up with for the variable factor were: the quantity of either the acid or calcium carbonate, the temperature C, density or environment of which the calcium carbonate came from.. of course not all of these were practical, and as a class we decided that the concentration would be the variable. Concentrations we had to work out but the other three were given to us. Here are the concentrations given in table format:
As you can see the two-I bullet pointed are the concentrations I had to figure out and use to make the solution. *M=mole, which the means the units used for the concentration of acid.
Fairness: I will make the test fair by weighing the amount of calcium carbonate used and making sure it is 4g for each experiment. I will also make sure that the solution is of 20cm3 and no less. As for the temperature C, that will be at room temperature C.
Safety: To make this test safe I will conduct this experiment as far as possible from the edge, so nothing spills. Also I will have goggles on at all times for the protection of my eyes.
Secondary sources:
*
A mole is defined as
the number of atoms in exactly 12 g of 12C (carbon twelve).
In the above definition, 12 is the of carbon.
So, one mole of carbon atoms has a mass of 12 grams.
The relative atomic mass
is the number just above the element in the periodic table
(have a look, and check that carbon is 12).
If you don't know what "relative atomic mass" means,
see in the Atomic Structure section.
*Collision Theory
A chemical reaction can only occur between particles
when they collide (hit each other).
Particles may be atoms, ions or molecules.
There is a minimum amount of energy
which colliding particles need in order to react with each other.
If the colliding particles have less than this minimum energy,
then they just bounce off each other and no reaction occurs.
This minimum energy is called the .
The faster the particles are going, the more energy they have.
Fast moving particles are more likely to react when they collide.
You can make particles move more quickly by heating them up
(raising the temperature).
Source http://gcsechemistry.com/rc1.htm
Results:
OOT= out of tube
As you can see from the results that each section has two results. That is because I did the experiment twice to get an accurate average. Below on the next page is the table drawn again with just the averages. The answers are all in mm.
I am now going to take the 10second column and divide each number by 10, giving me the initial rate in mm/s. I am not going to take the five second column because it has a few noughts in it, and I am sure that there was gas given off but not visible by the naked eye.
I shall now plot graph to present my results and the analyse them.
Conclusion: On the whole I would say that my prediction was correct, which was that if the concentration of the acid would be directly proportional to the length of time. Obviously my results are not entirely correct based on certain other factors. Also the line of best fit was drawn to what my prediction was. Most of my results were close to the line of best fit and did not vary too much. But there was one result that did not match in particular that did vary a considerable amount more than the others, which were circled. Reasons why it varied considerable amount more than the other results could depend upon many factors, for example, just someone walking by may have heightened the room temperature to a certain degree, or performing an experiment, and the gas leaked and affected my results. To control this unexpected variable I would have to conduct this experiment in an isolated environment where there are no outside distractions/influences.
Evaluation: I consider my evidence (results) to be reliable and non-reliable. I think this because if it is just to see what happens then my results are quite reliable, but then if my results were purely based for scientific purposes, then the manner I conducted it in had to many variables beyond my control. For example:
- Room temperature means anything between 19-21 Celsius. To improve I would need to have a set temperature with no influences.
- Surface areas of calcium carbonate were not the same, so based on collision theory the smaller that are the longer it takes as it is more difficult for acidic particles to reach it.
- There is always the factor of human error, which can be minimised with precautions but not demolished. The precautions we could take could be wash everything we used to make sure it is neutralised etc.
As I said earlier in the conclusion there was one result that varied to an exceptional amount, which was circled. Possible factors that may have had an effect on this were, the temperature, the calcium carbonate, environment form where the calcium carbonate came from e
The two sets of results I achieved were very similar, but there were some with a bit more varied differences. On the whole they were quite accurate. There some, which went completely wrong that, is why we have the averages.
I could have also taken another set of initial results, but It would have to have been 15 second, as more time passes the longer time it takes to react as there is less to react with.. that would have given me even more accurate readings to a certain extent.
If I went further with this experiment, I would try and find out how much concentration of acid it would take to react with one gram of calcium carbonate. To work it out I would either have to use the method of trial and error, or work out how the gas given off is linked with what I need to work out. If I did do this experiment successfully I would’ve shown how long it would take for one gram to react.
The usefulness with this would be that we would know how much acid to put in and not waste any, as an added bonus, the solution should become neutralised, as there would be only enough particles to react with enough calcium carbonate, so the acidic and calcium particles should react and go, therefore leaving water which is not harmful either. The downside would be, if you were testing the speed, the more acidic particles there are, the more area they cover, therefore reacting with the reactant much quicker.
