2.3 In this experiment we will be testing two factors, concentration and temperature of the chemical reaction. And we will be working out a conclusion for the affects of concentration and temperature on the reaction rate and the ability to double the reaction by doubling the concentration and the temperature.
2.4Method
2.4.1 List of Equipment:
- Calcium Carbonate (marble chips 24gm- 3gm for each single test)
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Hydrochloric acid CaCO3 (130 ml, different size for each test)
- Deionised water (110 ml)
- Thermometer
- Weighing scales
- Beaker
- Stop watch
- Matches
- Tripod
- 250 ml Measuring cylinder
- 2 Clamps
- 2 stands
- Side arm flask
- Fireproof mat
- Delivery tube
2.4.2 Explain Method
First part of the experiment, we fill the beaker with tap water about half way, and filled the measuring cylinder with water and then turned the measuring cylinder upside down as shown in the diagram below. By doing this we did create a slight margin of error because some of the water was displaced when doing this although it was very little. Then we clamped the measuring cylinder in place. We changed the size of the cylinders; however, this did not make the test unfair. We then put the delivery tube inside the measuring cylinder so the air from the experiment could displace the water. To make sure the volumes of acid and water were right we now measured the volumes of each in a measuring cylinder to be accurate. To make sure the mass of marble chips were right; we used the electronic balance by two decimal place to measure the mass of the marble chips. Then we put the chips and the acid in the conical flask and started the stopwatch.
As the experiment has started we now recording the time to produce a 50cm3 volume of CO2. We did this four times. Every time we change the marble chips (fixed mass of marble chips for all tests) and the concentration of acid for each test as (0.1M, 0.08333M, 0.06666M, 0.05M) until we had all the data that was required. While doing this experiment we had to work carefully to avoid accidents and follow safety procedures
2.4.3 Second part of the experiment, we heat 30ml of HCl with a concentration of 0.044M to50°C. Then the heated solution would be added to the conical flask, that’s after measuring the Calcium Carbonate mass; we would be able to add that to the conical flask. To keep the experiment fair we need to always place the acid first then the Calcium Carbonate or the opposite, this must be done all the time. As we add both reactants to a conical flask, we must immediately place the cork onto the flask as it’s shown in the diagram below, the gas collected would be CO2. The range of temperature would be used is 50, 70, 90°C as this range is a safe range and enough to receive a reliable result.
The first experiment will last by producing a 30cm volume of Carbon dioxide; the time to produce the fixed volume of CO2 will be the result of our reading. By doing the test three times using 50,70, 90°C temperature and record the time for the reaction to happen when it was 50, 70, 90°C. We used the same concentration on the three times and the same mass of the Calcium Carbonate, we also had to make sure that the amount of CaCO3 must be kept constant so we used 3gm of Calcium Carbonate each test. In addition, we used a stopwatch to measure the time soon as the reaction start.
- a) Variables kept constant. Firstly the mass of the chips was kept as similar as possible, we did this by weighing the chips to be at an approximate mass of 3.0gm on electronic balance scales.
b) From a previous chemistry class I found that the surface area greatly affects the rate of reaction, therefore the marble chips were separated by hand using a sieve to obtain pieces of medium size.
c) Another variable we took into account was the volume of HCl will use, we chose to use measuring cylinder to measure exactly 30ml for the first test. Followed by 25ml of acid with 5 ml of deionised water, 20 ml acid-10 ml deionised water, 15ml acid -15 ml deionised water. Also I intend to measure the initial temperature of the room before the experiment with a Thermometer it was 22°C.
- Concentrations of HCl 0.1M, 0.08333M, 0.06666M and 0.05M . To obtain these different concentrations we used a solution of 0.1M, which was already prepared. However in order to create a 0.05M, 0.08333M and 0.06666M solution we had to mix different solutions. The 0.05M solution was made using 15ml of deionised water and 15ml of 0.1M solution; this was then stirred with a glass rod. To make 0.08333M solution the same concept was used, I mixed 25ml of 0.1M solution with 5ml of deionised water. And to make 0.06666M, we mixed 20ml of 0.1M solution with 10ml of deionised water.
- Other factors are what kind of water to use, I could either use water from the tap, which is not very pure, or it may be too hot or too cold, so we used deionised water.
- Temperature kept constant, by controlling the heater and moves it away when the temperature is over required.
3.1. Results
The result are summarised as the following tables and graphs.
(Concentration to produce 50cm3 of CO2)
Reaction Rate when Temperature Increase
3.2 Graphs
3.3. Calculations
a) In this experiment I have to find the concentration for HCl when it’s mixed with
M1v1=M2V2
M1 concentration before
M2 new concentration
V1 volume before adding solution
V2 the new volume
By adding 5 ml of water to 25ml of HCl
M2 =M1 x V1 /V2
M2= 0.1 x 25/30 = 0.08333M
Following these steps we can find the concentration of solution we used in our experiment
2 by adding 10 ml of water to 20 ml of HCl the new concentration will be
0.1 x 20/30= 0.0666M
3 by adding 15 ml of water to 15 ml of HCl new concentration is
0.1X 15/30= 0.05M
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From the first graph it takes 220 second to produce 50cm3 of CO2 when the concentration is 0.052M, but it takes 110 second to produce the same volume of CO2 when the concentration is 0.1M but I can see that
Concentration 0.052 M ≈ (half) x 0.1M
But when the concentration for HC is 0.1M it takes 110 second to produce 50 cm3 of CO2, which is, halve the time when the concentration is 0.052M
So I can conclude that when the concentration is doubled the time will halved, which is mean reaction rate will be doubled when the concentration doubled and that clear on the graph which is agree with my previous prediction.
- From the second graph I took two pionts
To produce 30cm3 of CO2 in a time of 180 second the temperature was 52°C
However it takes 90second to produce 30 cm3 of CO2 when the temperature is 66°C. My conclusion when I read my graph that the reaction rate will be doubled when the temperature increase by 14°C and that’s the different between the two temperature
66°C - 52°C = 14°C
4.1. Interpretation
The graph above supports my original prediction, the more (concentration) acid the faster the rate of reaction. And doubling the concentration will double the reaction rate, because it shows the time difference between the different strengths of acid and the concentration. In a higher concentration there are more acid particles to react with the CaCO3 and therefore it is produce CO2 faster. But with temperature. I found from my teacher that double the reaction rate by temperature also need an increase by about 10°C , in my experiment I found that increasing the temperature by 14°C does have a significant effect on doubling the reaction rate as in the graph. In conclusion this not in agreement with my prediction that doubling the temperature will double the reaction rate.
4.2 Evaluation
4.2.1 I evaluate that first part of the experiment was successful and got reliable results (testing the concentration). Although the second part (testing temperature affect on reaction rate) there was space for improvement. The resources available for the experiment was limited, therefore I was not able to use sophisticated devices. The results could have been more accurate and more reliable if I was able to use the computer and sophisticated equipment to take the results such as a temperature detector. If I was able to use them then I will get much more reliable results and the percentage error will be very insignificant
4.2.2 There were a couple of points for the experiment to be improved by, first that by adding the CaCO3 and quickly placing the cork on top will lose time and some of the immediate product is lost. Also that a normal person pressing the time is not the most accurate of techniques. This obviously increases the error percentage in the results making the result outcome slightly incorrect. One way to improve the experiment would be to use a cork with two holes fitted with valves. One to enter the acid and CaCO3 powder and one connected to the syringe for the product of the reactants to be let out. In my view, I find this a more reliable technique.
In addition found it very hard to measure out the exact time to produce 30cm3 of CO2, even though I used a stop watch and we were also in a hurry. If I were to redo this investigation I would put some more effort into measuring the time. The size and weight of the CaCO3 would have affected the rate of reaction. The experiment could be improved by measuring, adjusting, CaCO3 they all are the same size and. I also found out from background information, that the CaCO3 is covered with a whitish deposit. This deposit was calcium oxide where the calcium had reacted with the air. I would imagine that some pieces had only a little of this oxide and some had a lot. The pieces of CaCO3 that did not have much oxide on them reacted faster than those with a lot. To improve my results, I could clean the calcium oxide of all the CaCO3 pieces using some sandpaper, and this would mean that the acid would not have to eat through the calcium oxide before reacting with the calcium. In my investigation I also measured the temperature to see if there would be any change in the rate of reactions. From my results it was noticeable to look at each experiment and see how the temperature had affected the rates of reactions. For instance, if we refer back to the table and look at experiment, test three is slightly faster than test 1 or test 2 because it has a temperature of 90ºC, where as the other two tests both have a temperature of 50,70ºC. But in this situation we try to keep the temperature sharply 50 or 70 or 90ºC, but I m assure there is an error in acid temperature as we kept the heater on and off trying to have the right temperature and that’s really hard to control unless using other technology which is not available at the time .
Conclusion
Firstly my conclusion is that the experiment was successful and that the results were reliable to make a conclusion from, and I will conclude that double the concentration of the acid does affect the rate of reaction and double it.
Secondly I conclude from the experiment that the temperature will affect the rate of the reaction between HCl and CaCO3. This is because when the temperature was raised the particles will vibrate more making them react faster because the amount of collisions will be higher and faster. Therefore I will conclude that doubling the reaction rate is possible by increasing the temperature by 14ºC from my graph, which is wrong, however increasing the temperature 10ºC will double the reaction rate.
Finally, when the concentration is double the time take for the reaction should be halved. Also when temperature increased by 10ºC reaction rate will halve because energy of collisions in the particles increases, this means that there are going to be more successful collisions and reaction rate will double.
5. Real World Context
5.1 Acidity is measured on the per-hydrogen, or pH scale. This is a measure of the concentration of positively charged ions in a given sample. It ranges from 14 (alkaline or negatively charged ions) to 0 (acidic or positive ions). Pure water has a pH of 7 (neutral). Most rainwater is slightly acidic (pH about 6).. Generally rain with a pH value of less than about 5.3 is considered acid rain.
Acid rain occurs when sulfur dioxide and nitrogen oxides are emitted into the atmosphere, undergo chemical transformations and are absorbed by water droplets in clouds. The droplets then fall to earth as rain, snow, or sleet. This can increase the acidity of the soil, and affect the chemical balance of lakes and streams. By increasing the concentration of acid, Acid rain also can damage certain building materials and historical monuments. When acid react with limestone and the more concentration the more damage will happen, as in my experiment when concentration increase reaction rate will doubled.
Some types of rocks can reduce (neutralize) the acidity of the rain, whereas other rocks have no effect. Calcite (CaCO3) and dolomite [CaMg(CO3)2] are two minerals that greatly mitigate the effects of acid rain; calcite and dolomite are the principal minerals that make up the rocks limestone and dolomite, respectively, as well as marble. For example, the case of sulfuric acid falling on limestone can be summarized by the following reaction:
H2SO4 + CaCO3 --> CaSO4.H2O + CO2
The sulfuric acid is neutralized as the mineral gypsum (CaSO4.H2O) and carbon dioxide are produced. Lakes located on, or rivers flowing through, limestone terrains will be neutralized; they will not suffer the consequences of acid rain. The same would be true in dolomite or marble terrains.
acid rain is a form of chemical reaction which create from the nature ( in other ward there is no control over its variable, in my experiment I have a full control over the variable of the reaction rate , especially the concentration , that’s the different between the chemical reaction in my experiment and acid rain , but we have to notice in country where the sulfur dioxide and nitrogen oxides found , more acid rain will form as the concentration is higher .when acid rain fall its react with limestone rocks and building , and this will cause a damage for these Buildings .
- risk assessment
The safety of this experiment is very important. The things that I will need to do to keep my experiment safe for myself and other students around me are as follows:- 1- Wear safety goggles as I am using hydrochloric acid which can irritate the skin, Care to eyes and the skin besides all the other people is always vital and necessary,2- Care in using glassware since it is sharp when broken and can cut skin. 3-Safe disposal of reagents and laboratory chemicals, 4-Care when returning all used glassware and equipment at the end of the experiment
6 References
1 Campbel .J A, Piementel. G (2002) Rate of Chemical Reaction, wards natural science establishment, Wexler Film, New York, USA [video recording]
This video provides detailed information and clarifies different chemicals issues related to rate of chemical reactions.
The video aims to introduce the following concepts; simple reaction mechanisms, activation energy, the activation complex, factors affecting rate of reaction and related topics.
I found the video informative and helpfully for my investigation, also its help me on my practical experiment and shows how to deal with the experiment equipment. Finally, it was published in the year 2002
which is a reliable resource to use for few reasons I mentioned previously.
2 Connors.K A, (2001) Reaction Kinetics: The Study of Reaction Rate in Solution, VCH Publication, New York. USA
This chemical Kinetics book blends physical theory, chemical reactions and provides a guide to the experiment practice and interpretation practice of reaction kinetics in solution.
This book explore a discussion of study reaction kinetics and factors affect the chemical reaction such as, time, temperature, concentration,
It is useful for my investigation and relevant to the subject, it is a good introduction to theories of reaction dynamics, reaction in solution, and it’s describe various experiment techniques which I found useful and reliable source for my investigation.
3 Laidler.K J, (2001) Chemical Kinetics 3rd Ed, Harper Collins Publishers, New York, USA
This book presents the more important experiment result and theories relating to the rates with which chemical reaction occurs.
regarding to the author this book made improvement in the treatment of chemical reaction topic , and include a suggestion s by a number of experts like Professor Robert A, John Anderson and others ,
I think this book is a rich source with chemical information and its contain good academic level of chemical explanation and theory.
4 Tsuge. S, (2001) “Rate Increase in Chemical reaction” (visited 25 Aug 2004)
This website provides a summary on the affect of temperature and concentration on rate of reaction, its clarify the theory of collision and the affect of factors on reaction rate, also its shows different method to carry out an experiments for student who are they interested in this subject, the website is supervised by a staff of TARA Centre, University of Tsukuba, Japan which is a reliable academic source.
I found the website is helpful and its directly related to my topic , and there is a good useful information to improve my idea in practical experiment and theoretical issues related to chemical reaction ,activity energy , collision theory , rate of reaction, its also provides a valuable of suggestion for the chemical reaction experiment .
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whitaker.B, (2003)Molecular Dynamics, Cambridge university press,
Cambridge, UK
This book explain the basic principles of experiment and the numerical method involved in interpreting experiment data it contains discussions of basic chemical experiment and goes onto review image reconstruction techniques.
It is useful reading in that it helps me understand the technique of interpreting experiment data, it’s a primary interest to researchers and high school students working in chemical reaction and molecular physics who require an overview of the subject.
