To Discover What Affects the Rate of Reaction Between Marble Chips (Caco3) and Hydrochloric Acid (Hcl)
Chemistry coursework
AIM: The aim of this experiment is to discover what affects the rate of reaction between marble chips (CaCo3) and Hydrochloric acid (HCl)
PLANNING: My group and I are going to measure the amount of gas given off from the reaction between CaCo3 and HCl. We are going to time the reaction and measure the amount of gas in the graduation tube, recording the amount every minute. We are using three different sized pieces of CaCo3: small (< 0.5cm diameter), medium (( 0.5cm < 0.7cm diameter), and large (> 0.7cm diameter). For each of the three different experiments we used the same mass of CaCo3 (0.5g) although the surface are was very different for each experiment because of the different sizes of CaCo3.
VARIABLES / FAIR TEST: The variables are the things in my experiment which can change and alter my experiment. The first variable is the marble chips, the surface area and the mass of these can change. I am purposely changing the surface area for my experiment although I will want the mass of the marble chips to stay the same for each experiment.
The second variable is the room temperature because if the room temperature alters throughout the experiments the results could also alter. To make this a fair test I am going to carry out the three experiments in the same lesson so that the room temperature and therefore the HCl temperature hopefully remain the same.
PREDICTION: I predict that the experiment using the largest surface of CaCo3 area will have the fastest reaction time, because the larger the surface area of the solid, the higher the chance of a collision. This means that more collisions mean more reactions between the particles. Therefore, the larger the surface area, the quicker the reaction occurs. This is part of the collision theory.
I also predict that the other two experiments will follow accordingly, i.e the medium size surface area of CaCo3 will have the second fastest reaction, and the experiment with the smallest surface area ...
This is a preview of the whole essay
PREDICTION: I predict that the experiment using the largest surface of CaCo3 area will have the fastest reaction time, because the larger the surface area of the solid, the higher the chance of a collision. This means that more collisions mean more reactions between the particles. Therefore, the larger the surface area, the quicker the reaction occurs. This is part of the collision theory.
I also predict that the other two experiments will follow accordingly, i.e the medium size surface area of CaCo3 will have the second fastest reaction, and the experiment with the smallest surface area will finish last. The rate of reaction for all three experiments should be a smooth curve, which gradually slows down.
APPARATUS: The apparatus needed for this experiment is as follows:-
* Conical flask,
* 150ml of HCl,
* 1.5g of CaCo3
* Graduation tube.
* H2O,
* Rubber bung,
* H2O reservoir,
* Flexible glass straw thing ????,
* Stop watch,
* Scales
SAFETY: This experiment was a low risk experiment, as the only thing which could cause a hazard, and which we had to be careful with, was the HCl. This is an acid and therefore dangerous if it was to get into someone's mouth, eyes or skin. It can burn and cause great pain. To make the experiment safe, each time we used the HCl we washed our hands.
FAIR TEST: We followed a number of steps to make sure that this experiment was as fair as possible:
* We carried out the three experiments on the same day so that the room temperature remained the same,
* We used +0.00 scales so that our measurements were very precise,
* We used the same set of equipment for each experiment,
METHOD: We started by measuring 3 separate amounts of CaCo3 (small, medium and large) (0.5g) and we then carefully poured 50ml of HCl into a conical flask. We then set up the apparatus as shown on the next page. We had to fill the graduation tube up fully with water, then block the hole with my finger, so no water could leak out. Then I had to quickly turn it upside-down and place it in the H2O reservoir and attach the clamp stand to it, this would keep the water in the graduation tube. Once this was all set up correctly we started the experiment by lifting the bung up and dropping the marble chips into the conical flask with the HCl. We started with 0.5g of the small chips. As soon as the chips were in the conical flask we placed the bung back into the conical flask and started the timer.
Straight away we could see bubbles coming up the graduation tube and pushing the H2O out of the bottom. We started to record to amount of gas at the top of the graduation tube after the first minute. We then continued to measure the amount of gas given out each minute for twelve minutes. We recorded all of the data accurately in our books, and then we reset the experiment. We carried out exactly the same experiment twice more, but using the different sizes of CaCo3 each time. Once we had finished we cleaned up and started to draw up the graphs and charts showing our results we had obtained.
DIAGRAM:
RESULTS:
This table shows the results for each of my three experiments
Min from start
Small chips (mm of gas)
Medium chips (mm of gas)
Large chips (mm of gas)
Average (mm of gas)
0
0
0
0
0
5
5
6
2
2
30
28
0
23
3
43
40
6
33
4
55
51
21
42
5
65
60
26
50
6
73
68
33
58
7
77
74
38
63
8
79
77
43
66
9
81
81
49
70
0
81
83
53
72
1
81
83
59
74
2
81
83
63
76
As you can see from the graph above, there is a very significant difference between the small and medium CaCo3 to the large CaCo3. This is because the large piece of CaCo3 was one piece and so there must have been a very significant difference in the surface area.
What also is very noticeable is that the small and medium CaCo3 both completed their reaction at around 10 minutes, but the large CaCo3 continued to react after the experiment had finished. This is also because of surface area, as I mentioned in my prediction "Therefore, the larger the surface area, the quicker the reaction occurs." This is simply a continuation of the reaction because of the larger surface area.
EVALUATION: The anomaly in this experiment may not be very obvious, however you can see that the final figures on the graph recording the small and medium CaCo3 alter by around 3mm. If this was a perfect experiment the figures would be exactly the same, therefore the error is caused by slightly inaccurate measuring of the CaCo3 at the beginning of the experiment. It is however very difficult to be extremely accurate when the mass of each chip is so small.
To improve this experiment for the future we could introduce such variables as:
. Use a higher amount of HCl.
2. Use a higher amount of CaCo3.
3. Use a smaller amount of CaCo3.
4. We could also experiment with totally different surface area sizes, e.g. all > 2.0cm diameter.
We could also alter the experiment drastically to see what effects it will have on the results, if any. We could:
.Use different strengths of HCl
CONCLUSION: By carrying out this experiment I have discovered that mixing HC1 and CaCo3 together causes a chemical reaction in which gas is given off. The speed of reaction between HC1 and CaCo3 can be altered significantly by simply altering the surface area of the solid, in our case CaCo3. It is possible to record this data accurately on a graph.
