Type: Research Essays
Sample donated: Stacey Little
Last updated: March 18, 2019
CLAIRE MUNTING 29/01/2018Criterion C EFFECTS OF SURFACE AREA OF CALCIUM CARBONATE UPON RATE OF REACTION Calcium Carbonate Chips 1Introduction: Within the current investigation, the effects of the surface area of Calcium Carbonate (CaCO3) in combination with Hydrochloric acid (HCl) upon its rate of reaction. CaCO3, commonly referred to as limestone, is an organic substance and is, in a sense, the crystallised “carbonic salt” of the element, calcium2. In addition to being a salt, the pH level of Calcium Carbonate is 9.91, and it is therefore, a basic substance, due to the fact that it is comprised of a pH level higher than 7, which is neutral3.HCl, however, is the bodily acid found in the stomach of human beings. It is secreted by the oxyntic cells in the gut which are found within the oxyntic glands of the stomach lining. The substance is colourless yet remarkably corrosive, and is therefore able to be the primary digester of food in an individual4.
The liquid’s pH level is a highly dangerous, yielding 1, though it may vary slightly due to its molarity (# of molesliters of solution), but nevertheless is deemed a strong acid. When the two are combined, CO2 is released, and so the their rate of reaction may be measured by the pressure of the resulting gas5.AimAs aforementioned, the intent of this experiment is to highlight the forms in which the surface area of CaCO3 affects the rate of reaction, as measured by the CO2 gas production, when added to 20 ml of a 1M Hydrochloric acid solution.
The Balanced Equation Indicating Products and Reactants is:CaCO3 (s)+2HCl(aq) CaCl2(aq)+CO2 (g)+H2O(l)Changes To Method:ChangesBrief ExplanationUsed 20 ml of Hydrochloric Acid in Place of 10 mlSmaller Erlenmeyer Flask was UsedThe Investigation Yielded 18 Trials in Place of 12Used a Folded Paper Funnel Instead of Hands to Input Calcium Carbonate ChipsSince I could not know to what extent 10 ml of Hydrochloric acid would cover the Calcium Carbonate chips, an educated guess was formed.This approximation of the amount of acid seemed to be better suited with 20 ml, as it ensured that all chips would be comfortably covered in the acid.The use of the smaller Erlenmeyer flask was quite circumstantial. It required that a smaller absolute pressure sensor was found, and that there were sufficient small flasks. In the end, the newly-found flasks seemed to be better tasked to fitting the chips and acid suitably so that neither would overpower the other.Primarily, it was believed that the amount of time in class would not be sufficient for 3 trials for each diametre in total, therefore, it was reduced to two. However, when it was revealed that a class period could pleasantly accommodate 18 trials in one sitting, the investigation was adjusted to record more trials, resulting in improved overall results.Finally, the use of a folded piece of paper so as to funnel the Calcium Carbonate chips into the Erlenmeyer flask is courtesy of Mr.
Holz. The initial idea was to, as quickly as possible, input the chips into the flask, yet it resulted in quite a bit of mess. Thus, the folded piece of paper allowed for one to both dry the chips for re-use, and funnel them smoothly into the flask for ample trial periods.Raw Data:Processed Data:Throughout the investigation, all trials were successful and therefore did not result in any discarded trials. Sample CalculationSo as to achieve beneficial results from the collected raw data, one must manipulate it so that the data is formed in such a manner so that an analysis of it is clear. Therefore, the formulas and mathematical applications of the results were: the proportional scaling of the surface area, and the averaging of certain numbers.
Firstly, the surface area per particle must be adapted to demonstrate the surface area per 5 grams, which was the controlled amount throughout the investigation. To do this, the original figure should be multiplied by the amount of such particles in 5 grams, as shall the uncertainty.Ex.572.55 m210-6 = Surface Area Per ParticleApproximately 2 of the given particles will result in a mass of 5 grams.2 (572.
55 m210-6) = Total Surface Area1145.10 m210-6=Total Surface AreaHowever, the uncertainty for the surface area must be kept proportionate. So: ±85.88 m210-6=Uncertainty of Per Particle Surface Area2 (±85.88 m210-6)=Uncertainty of Total Surface Area±171.77 m210-6=Uncertainty of Total Surface AreaSecondly, the average rate of reaction, as measured by the rate of CO2 gas production, must be calculated, in addition to its uncertainty.Ex.
Three Rates of Reaction: 1) 1.72kPa/s2) 1.75kPa/s3) 1.79kPa/sTo find the average, take the sum of the rates, and divide by the amount of rates:1.72+1.
75+1.793=Average Rate of Reaction5.263=Average Rate of Reaction1.75kPa/s = Average Rate of ReactionThen, to find the average of the uncertainties, repeat the method:.052+.
082+.0963=Average Uncertainty.233=Average Uncertainty.077kPa/s=Average Uncertainty*Due to the fact that the amount of particles per 5 grams, I could not collect, the information was collected by Kamryn Schult and utilised in the calculations above*Data ResultsThrough use of the processed data above, below is a formatted graph visually indicating the results.Analysis of Data: As indicated within the aforementioned graph and data tables, the general relationship between the independent variable, being the “Total Surface Area of CaCO3”, and the dependent variable, being the “Rate of Reaction as measured by CO2 gas production”, is that as the independent variable increases, as does the dependent variable. When visually portrayed, one may notice that the connection is most accurately described through the use of a logarithmic trendline.
Therefore, the assumption could be made that the increase of the total surface area will eventually reach a plateau. This is in fact correct. As the diametre of the Calcium Carbonate chips is reduced, the stability of its form was also reduced. This could could be expressed by showcasing that at a certain point, the furthest to which the physical shape can be decreased is to a dust. Theoretically, when the CaCO3 is dust, the amount of surface area which is exposed to the Hydrochloric acid has reached a maximum, so proving the concept that the graph would eventually stabilise and no longer increase in the y-axis.
Also, it must be taken into account that the data is reliant upon the fact that though the diametre of a Calcium Carbonate chips may be large, its amount of surface area in proportion to the amount of particles per 5 grams is far less than that of a smaller diametre chip. For example, a chip with the diametre of an average of 13.5mm will have a surface area per particle of 572.55. On the other hand, a chip with the diametre of an average of 2.
75mm will have a surface area per particle of 23.76. At first glance, the larger diametre has a larger surface area, which is correct, yet neglects to acknowledge that solely 2 of the 13.5mm chips may comprise 5 grams of Calcium Carbonate, whereas an astonishing 164 of the 2.
75mm chips may comprise the same 5 grams. So, in the end, the much smaller diametre allows for more surface area, resulting in much more CaCO3 to react with the Hydrochloric acid instantaneously. Referring to the previously written investigation of method named “Effects of Surface Area Upon Rate of Reaction”, it was stated that as the diametre of Calcium Carbonate chips is decreased, and the surface area exposed to acid is increased, the rate of reaction will also increase6. Indicating that the if the independent variable were to increase, the average rate of reaction (the dependent variable) would grow in a proportionate manner.
Though it was not identified that the relationship may be logarithmic, the resulting values and data permits a conclusion that the hypothesis is accurate. With regard to an accepted scientific understanding, The Royal Society of Chemistry has stated that if the mass of an object remains constant, whereas its surface area is increased by subdividing that mass, the area available for reaction would increase. This addition of area would then allow for much more reaction to occur, enabling the particles to collide in a higher abundance, therefore, increasing the rate of reaction. Not only is the concept widely accepted, but the analysis previously mentioned that suggests that the surface area of the CaCO3 will level is directly supported7. Within the same source it is written that: “the end point of these divisions would be at a molecular level as they would be found in liquid, aqueous or gaseous form.
This is the ultimate ‘small particle’ to ensure a rapid rate of reaction”7. This quotation formally justifies the prior claim, as both agree that there is a maximum increase of surface area possible by decreasing diametre to a molecular degree. As for a scientific understanding of the results, one may turn to the subject of collision theory to rationalise the interpretations above. At its core, the theory requires three elements to be fulfilled if a fruitful collision is to take place. These three are: that the orientation of the collision is correct, the particles must contain enough kinetic energy for the collision to even occur, and lastly, that particles must simply collide. The first elucidates the form in which not every collision has the potential to be fruitful, and that if the orientation is incorrect, the particles will not bond8. Though the surface area of a substance will not alter the kinetic energy of its particles, it does allow for an increased prospect that primarily, particles will collide, and secondly, that they will collide in the proper orientation. So, an increased surface area produces a higher possibility for fruitful collisions to occur, therefore increasing the overall rate of reaction once more.
Strengths and Weaknesses:Reliability of DataIn general, the reliability of the results collected, and the data assessed yields a trustworthy outcome. If one were to refer to the raw data table, wherein the results of each individual trial are recorded, it would be encountered that the the difference between some data points for example the 12 to 15 mm is mere 0.07 range.
This minuscule difference in data points allowed for an insight into the form in which the overall result of the investigation is reliable. In addition to the singular example, as a general observation, there is an absence of outliers within the trials and an abundance of samples and trials wherein not much variation can be seen. With direct reference to the graph of processed data, the use of a logarithmic equation for the trendline of six data points, allows for a close match within the results and the curve. Not only could raw data be analysed, but the error bars present within the graph may offer a clear understanding of how each point may differentiate from the next and how each point is trustworthy in its own. As can be seen the horizontal error bars for each data point or proportionate to the rate of reaction. This is due to the fact that an approximation of the variance of the surface area throughout each chip or diameter would be about 15% of the overall surface area.
This will be an account for the circumstances wherein a calcium carbonate chip may be an almost perfect sphere, but also the cases in which the vertices of the chip barely resemble a sphere and are more suited to the shape of a cylinder. Furthermore, the vertical error bars are very indicative of a reliable set of data. Already if one were to view the graph, one would recognise that some error bars are so miniature that the chart is not able to draw them in the proportions given. The vertical error bars therefore represent the unreliability in the averages of rates of reaction, measured by Pasco capstone, the accuracy of the calculator is rather undeniable. So both the position of the approximation of range in the surface area, the computer software’s ability to precisely record range in the rate of reaction, and the lack of extreme outliers in the data collaborate to provide the viewer of the data with comforting feeling that the investigation is based upon just merit.Strengths & Weaknesses of MethodFor the strengths within the method, there are three main aspects which are regarded as most important, or most influential to the investigation, and therefore it is very beneficial to have these as stronger points of the task. The three are:Keeping the Molarity and Amount of the HCl ConstantThe Use of a Smaller Erlenmeyer FlaskThe Use of Pasco CapstoneFirstly, so as to maintain the molarity of the Hydrochloric acid, the given stock solution was utilised. However, the importance of this variable cannot be understated, as if the solution were to have been diluted with another substance, then the entire experiment’s results would be skewed, and it would probably be deemed inconclusive.
So, the presence of a definitive 1M stock solution removes doubt. Continuing, the amount of the HCl was also quite precisely kept at a consistent 20ml. Through the use of a precision instrument such as the graduated pipette, which features a 10ml scale and a bulb for suction of the liquid at the end, the maximum percentage of error of the amount of HCl would be a 1% error.
Secondly, the use of a smaller erlenmeyer flask, which was also one of the adaptations made to the method, allows for less Hydrochloric acid to be required so as to fully cover the Calcium Carbonate chips. The flask would supply the investigation a more precise result, as the coverage of CaCO3 by HCl would not be called into question. Therefore, less agitation would be needed as well, which could have tinkered with the overall values of the task.Lastly, the use of Pasco Capstone as a recording software for the CO2 gas production, and so, the rate of reaction was a highly beneficial resource. Since the program features built in formulas for the approximation of reliability and unreliability, the real-life connections of the values could be stated both visually and numerically since Pasco immediately created a graph for each trial, and could offer information about the points themselves. Regarding these points, the settings of the device were set to record 20 data points per second, allowing for extreme precision.
All in all, the electronic version of data collection is far more accurate and efficient than many previous forms of collecting data.For the weaknesses within the method, the three most prominent aspects of this field are written as:WeaknessImpact on ResultImprovement SuggestionThe Time Difference Between Combining CaCO3 and HCl, and the Adherence of Pressure SensorAs the Calcium Carbonate chips were carefully added to the 20 ml of Hydrochloric acid, there is no possible way of starting the reaction as soon as the pressure sensor is on top of the flask. Therefore, there is some information that is lost with regard to the first couple data points that would have recorded the initial increase in rate of reaction when the chips were added to the acid. Though the loss of some results may not seem very influential, the calculations that Pasco Capstone then conducts are slightly skewed.
As the graph would assign a linear function to the data points, yet if the beginning of the graph indicates a sudden jump in pressure from the usual air pressure to the now rising pressure as the result of a reaction. In general, the results would then all be slightly higher than usual, as the sensor has only started recording since when the stopper is applied, not since the start of the reaction.Though the time between the recording and the true begin of the reaction will never be entirely seamless, there is a way to minimise the effect that the aspect may have upon the results of the investigation. The improvement suggests that if instead of inserting the chips into the acid and then applying the absolute pressure sensor after, perhaps one could do both at almost the same time. This would be possible if one were to use the same piece of paper folded in half to funnel the Calcium Carbonate chips into the Hydrochloric acid, but instead of shaking them in and then picking up the stopper to start recording, one could use the stopper to gently push the CaCO3 into the flask. By doing this, the end position of the stopper is directly over the opening of the flask, and can therefore quickly be inserted into the Erlenmeyer flask.
Though there may still be a slight fluctuation in results, this technique should improve many of them.Non-Spherical Characteristics of Calcium Carbonate ChipsThroughout the experiment, it was a given that with the unreliability of the Calcium Carbonate chips given, that there would be a definite variation in the shape of each chips in each trial. Later, when it came to calculating surface area and utilising these results to formulate opinions based upon the data, it was assumed assume that the chips would be perfect spheres. This would allow for the simple calculation of surface area to be:Surface Area: 4r2However, the reality is that no CaCO3 chips are perfect spheres, and furthermore, when observing the chips themselves, they seemed more cylindrical, at some times, than spherical. Therefore, the resulting calculations for surface area would most likely be larger than the actual value, as much of the area that a sphere may contain is simply not present in the shape of these chips.To rectify this weakness is not an easy task, since each Calcium Carbonate chip will remain unique, and there is then no set equation for the determination of the surface area of CaCO3 chips.
However, there could most definitely be an adjustment in the way in which chips are chosen to be part of the trials. This way gestures to the idea of electing chips that are more rounded instead of solely fulfilling the need of 5 grams of chips. Though this improvement may require an increased amount of time spent on each trial, if the CaCO3 chips are better selected, then the issue of having very different results could be averted. However, as previously mentioned, there is no one way to correct this issue as it attempts to categorise an entire variation of shape in one equation which is, unfortunately, not possible.Agitation of MixtureAfter combining the two substances and applying the absolute pressure sensor, one would have to agitate the mixture so that the Calcium Carbonate chips were properly distributed throughout the Hydrochloric acid, and that they would not remain on the bottom of the flask. In theory, if every trial was agitated in the exact same form, then there would be not variance in the control variable, and the agitation would work in its assigned form. However, since a human being is agitating the flask, there is no assurance that even two trials have been agitated perfectly the same, no matter how hard one may try. Therefore, if one were agitated more than the other, there is the possibility that the rate of reaction in Pasco Capstone seems to be increasing due to an increased agitation of the substance.
This would, once more, distort the results slightly, allowing for hesitation in some elements of the investigation.So as to improve upon the unequal agitation of the substances in the Erlenmeyer flask, one could refer to a given system in which the deviation between trials is at least reduced. Though this variable had been attempted to be controlled in prior instances, if one were to use a stopwatch to every second swing the flask forwards, backwards, then left and then right, then the unreliability of the data could be reduced.
In this sense, every second would be monitored, and though there is still much room for human error, it is greatly decreased, and will seem to pose less of a threat to the overall results of the investigation.Limitations in Amount of Data CollectedRegardless of the amount of data collected, and it seeming reliability, three trials per type of diametre were conducted, and for the sake of the investigation, and its larger applications to the scientific world, an increase in trials would allow for much more security in certain findings, and could possibly result in new findings and analyses of data. Though total of 18 trials were done, it seemed that there was approximately one whole lesson period remaining wherein more trials could have been conducted. However, regarding the values for the independent variable, the maximum amount of variations were used, thus suggesting that the amount of values for the independent variable may be a strength in the terms of the investigation. In general, the ranges for the independent variable are relatively strict in the sense of there solely being certain diametres that one could work with. However, these diametres were in a sequential order, and allowed for a suitable analysis, and conclusion, of how diametre influences the dependent variable, being the rate of reaction.
Nonetheless, all in all, the main limitation of the amount of data collected is simply, the amount of data collected. So, if the amount of trials could be increased, a much more confident conclusion could be formulated.Improvement:Suggestions for Increased Data CollectionsAs previously stated, one of the main concerns regarding data collection within the investigation is the sheer amount of trials conducted throughout the task. To repeat more trial, then, a main concern is the amount of allocated time for the use of ISA equipment and lab space. However, a consideration to be taken into account is the fact that the completion of the trials, 18 in total, was done in about 45 to 50 minutes. Subsequently, with the remaining class period that was allotted, a repetition of the entire method could have been conducted once more.
This would total 36 trial, six for each diametre. Though there is significant proof indicating that the conclusion reached is justifiable and correct, the doubling of all trials would allow for much more confidence in both the results, and many of the claims made based upon the results. Not only should the averages then mimic the true rate of reactions of the substances, but the improved results should then be able to assuredly present how the rate of reaction may differ between datasets, and may definitively prove the reasons for the graph following a logarithmic trendline.
Unfortunately, the amount of independent variable values available in the lab does not allow for an increased amount in the values, however, with less assumption, and more confirmation of the research question, which would be possible with an increase in trial numbers, the data would not only be larger, but stronger and more coherent in its conclusion that the rate of reaction increases as surface area does.Works CitedCalcium Carbonate. Karma Associate. http://www.
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aqion.de/site/191. hydrochloric acid. National Center for Biotechnology Information. PubChem Compound Database. https://pubchem.
ncbi.nlm.nih.gov/compound/hydrochloric_acid#section=Top.Acids, Bases, & the pH Scale. Science Buddies. https://www.
sciencebuddies.org/science-fair-projects/references/acids-bases-the-ph-scale.Munting C. Effects of Surface Area Upon Rate of Reaction.
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