Find out what changes the speed of the reaction between marble chips and acid.
The aim of this experiment is to find out what changes the speed of the reaction between marble chips and acid.
In this experiment, there are several variables that could be changed or kept the same. The list of variables is:
* Volume of acid
* Temperature of acid
* Size of the marble chips
* Mass
* Concentration of acid to water.
Out of these five possible variables, I will be changing the concentration of acid to water. I will keep the other four variables the same. The total volume of solution will be 50cm3 for each experiment. The temperature of the acid and water will both be at room temperature. The size of the marble chips will be small for each and every experiment.
My prediction is that the marble chips will react faster if there is more acid and less water. Therefore if there is a higher amount of water in the solution, then the reaction will go slower. I think this will happen because of the collision theory. The collision theory says that particles will react if they collide with enough energy. The colliding molecules must each have enough energy to break their bonds. When you increase the concentration of a reactant, there are more particles, which can collide successfully. If the reactants are in a solution, and said solution is concentrated ands the amount of water is small; the reactant particles are more likely to collide with each other. This means that if there is a lower amount of water to acid, the marble chip particles will collide more successfully, meaning the reaction will be faster.
I will do a preliminary experiment, before I do the real experiment. It is useful to do a preliminary experiment because it shows you where you have gone wrong, so you can correct any mistakes before doing the real experiment. It also shows you if you need to do any more or less experiments to sufficiently show the point of the experiment.
Below is a diagram to show how I set up the experiment:
To keep the experiment a fair test, we carried out the following things to make sure our results were completely fair:
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I will do a preliminary experiment, before I do the real experiment. It is useful to do a preliminary experiment because it shows you where you have gone wrong, so you can correct any mistakes before doing the real experiment. It also shows you if you need to do any more or less experiments to sufficiently show the point of the experiment.
Below is a diagram to show how I set up the experiment:
To keep the experiment a fair test, we carried out the following things to make sure our results were completely fair:
* Started the clock when the cork was put on,
* Stopped the clock when the gas fills the tube to the line that we put on the test tube marking where the volume of solution we were using had risen to,
* Kept the overall volume the same (50cm3),
* Kept the temperature of the acid and water the same each time,
* Kept the weight and size of the marble chips the same (5g of small chips each),
* Cleaned the flask each and every time after use, to make sure there are no bits of acid and marble chips left over.
List of equipment:
* Weighing scales
* 50g Small marble chips
* Hydrochloric Acid
* Water
* Measuring cylinder
* Beaker
* 100cm3 Conical flask
* Delivery tube
* Stopwatch
* Test tube
* Trough
Method:
. Set up the experiment as shown before
2. Weigh the marble chips, it should be 5grams for each experiment
3. Mix the right ration of acid to water in a separate beaker
4. Mark on the test tube where 50cm3 is
5. Pour the solution and marble chips into a conical flask and put the cork with the delivery tube coming off of it onto the mouth of the conical flask
6. Start the stopwatch
7. Watch to see when the gas fills the tube forcing the water to go below the line on the test tube
8. Stop the stopwatch
9. Record the results
0. Repeat the whole experiment 4 other times, but changing the ratio in the solution for each time.
On the following page, you will find our preliminary results.
Concentration Time taken
30cm3 of acid, 20cm3 of 56.75
Water.
35cm3 of acid, 15cm3 of 14.54
Water.
40cm3 of acid, 10cm3 of 22.82
Water.
45cm3 of acid, 5cm3 of 9.47
Water.
50cm3 of acid, no water. 8.33
The graph to go with these results would look something like this (it hasn't been drawn accurately, it is just a prediction graph):
From my preliminary experiment and results I can see that I don't need to improve the experiment in any way. However, to make my results and graphs better, I am going to do one more experiment, and from both results I will find an average.
Here are the results:
Concentration Time Taken (seconds)
Experiment 1 2 Average
30cm3 of acid, 20cm3
Of water 18.03 18.05 18.04
35cm3 of acid, 15cm3
Of water 12.54 13.08 12.81
40cm3 of acid, 10cm3
Of water 15.22 13.20 14.21
45cm3 of acid, 5cm3
Of water 10.19 11.38 10.78
50cm3 of acid, no
Water. 7.72 7.44 7.58
Below are the rates of reactions for each experiment. Each level of concentration has been given a number, from 1-5. 1 being the first concentration which was 30cm3 of acid and 20cm3 of water.
Concentration number Rate of reaction
55.43
2 78.06
3 70.37
4 92.76
5 131.92
Conclusion
From the results we got, we can clearly see that if there is more acid present in the solution, then the chemical reaction will occur quicker. Here is the equation for the experiment:
CaCo3(s) + 2H Cl(aq) CaCl2(aq) + H2O(l) + CO2(g)
The word equation for this is:
Calcium carbonate + hydrochloric acid calcium chloride + water + carbon dioxide.
This means that because there was a higher ratio of acid, the molecules have higher amounts of energy, therefore there were more successful collisions and that is why the reaction occurred quicker. My prediction was correct in saying the higher the amount of acid in the solution, the shorter time it will take to produce a certain amount of carbon dioxide.
To compare my experiment with other people's results show that our results are very similar.
From the graph we can see that it has a resemblance to my prediction graph, this means that my prediction was correct.
Evaluation
I think that the experiment went very well. I made sure all the things that will keep the experiments fair were in place.
To improve the experiment I could have the sample bigger, by doing more experiments and by having more varied solutions. The bigger the sample, then the more accurate the results will be.
On the graph there are a few anomalous results. Particularly for the 35 and the 40cm3 of acid experiments. I don't know why the results came up as they did on the graph. For these two experiments, I did nothing different, so there is no explanation for the anomalous results to have occurred.
