Subject: Rate of Reaction between Coke and Mentos

Research question: Investigate how the rate of reaction between (Diet) Coke and Mentos depends on the change of temperature.

Hypothesis:

In this experiment, I believe that the temperature will affect the rate of reaction between Coke and Mentos due to the excitement of the particles when the liquid is heated up.

Theory:

What is better than soda, candy, and explosions? The following experiment will combine those three adorable subjects. As children, we all attended or tried to mix Mentos and Coke for fun, just to observe the geyser it will create. This geyser can easily be made of Diet Coke and Mentos that you buy at the next corner store. These goods are easily affordable. Hence the experiment should be an accessible source of fun, especially for the children.

This experiment might seem familiar to you, and it is due to the similarity of the volcano experiment. However, the volcano experiment is using baking soda and vinegar to get a reaction. In consequence, a chemical reaction takes place because of the formation of another material. Thus, the Diet Coke & Mentos Geyser is the result of a physical reaction where nothing new forms, but only rearrangement takes place.

Then, by using Diet Coke, which is a soda, in this experiment provides some information involved in the reaction. Having a soda means that it full of carbon dioxide, and it is the reason why there are bubbles in the drink. The bottle contains high quantities of carbon dioxide in aqueous form. Upon opening a soda bottle, one can hear the gas escaping from the bottle of soda. In some cases, the escape is vigorous. This escape results in the spillage of some of the soda along with the expulsion of carbon dioxide.

The carbon dioxide gas present in the soda remains trapped. The bonds between the gas and the water are responsible for the entrapment. However, if the bonds are broken, in this case, by the Mentos, a physical reaction happens. The bonds are more breakable by the Mentos because, on its surface, there are little bumps that are the reason for a surplus of bubbles. These bumps mean that more carbon dioxide gas escapes. Therefore, the Mentos plays a significant role in this experiment because it is the component that will make the Diet Coke act as a geyser. Without the presence of Mentos, the reaction would not be strong enough to make the liquid spurt out. Otherwise, this reaction would happen every time that someone popped a soda open.

Afterward, having a soda as a reactant, it means that there is carbon dioxide that bonds with water. As a gas, carbon dioxide wants to escape from the liquid. However, when the bottle is closed, the gas cannot escape. It stays in the bottle because of the pressurized conditions. Thus, when the container is open, the gas is free to escape. However, the carbon dioxide is trapped under the surface of the liquid because the water forms a coating of tension. The surface tension of the water creates a blanket layer that prevents carbon dioxide from leaving the bottle when open. Only a small quantity of the gas manages to escape when one opens the soda bottle.

Then, the Diet Coke is used instead of regular coke or any other soda because there is aspartame in it. The chemical compound called aspartame reduces the surface tension of the liquid, which allows the carbon dioxide gas to escape quickly and create the usual eruption. Aspartame interferes with the integrity of the blanket like layer, allowing carbon dioxide to escape. The high quantity of the gas results in the emission of a strong force that results in the massive eruption of the components.

Following that, when the Diet Coke is heated up, the bonds between each molecule starts to react and be more likely to break their bonds and become a gas. So, by heating the liquid, it will allow the carbon dioxide gas to escape even more quickly than before, and the reaction will happen faster than if it was non-heated. This also refers to the surface tension that is decreased, which also provides the allowance to the gas to escape quickly.

The process of transforming the aqueous carbon dioxide into carbon dioxide gas is called nucleation, where the state of the carbon dioxide changes rapidly from aqueous to gas state. The formation of air bubbles accompanies as carbon dioxide gas escapes from the mixture. The creation of the bubbles is faster when the surface tension of the liquid is lower, as in the case of diet soda.

Despite the high activation energy of the soda, due to its physical properties such as roughness surface and the ability to readily dissolve into the liquid, the Mentos helps to reduce the activation energy and make the mixture reacts quite fast. Therefore, Mentos catalyzes the reaction.

Also, the formation of carbon dioxide gas into water causes the water to foam because the hydrogen bonding and the surface tension of the liquid want to maintain a connection between molecules. The foaming results in visible bubbling as the gas escapes from the liquid.

Overall, the reaction will more likely occur with Mentos and Diet Coke because of the specific properties of each. Concerning the Diet Coke, the aspartame will considerably reduce the surface tension of the liquid than a regular coke with sugar or corn syrup. Then, the structure of the Mentos will be more effective than anything else. It is due to its density that will allow the candy to sink rapidly in the liquid. Also, another factor that will affect the reaction is the temperature. By heating up the liquid, it will allow the carbon dioxide gas to be more soluble in the liquid, which means that the gas will escape faster and easier, resulting in a quicker reaction.

Furthermore, the conducted experiment will use coke to compare the difference between the reaction with a liquid that contains aspartame and another that doesn’t include the chemical that helps to react faster. It will be useful in terms of analyzing data to understand how aspartame is a factor of the rate of reaction between two similar liquids at the same temperature.

Materials:

• Two 2-liter bottles of Diet Coke
• Two 2-liter bottles of coke
• A full package of Mentos
• A camera
• Goggles
• 125ml Erlenmeyer
• 100ml graduated cylinder
• Hot plate
• Thermometer

Methodology:

1. Pour 100mL of Diet Coke in a graduated cylinder
2. Pour the Diet Coke into an Erlenmeyer

• Heat the Erlenmeyer to SATP using a hot plate

1. Place the Erlenmeyer on a flat surface
2. Drop a Mentos carefully in the Erlenmeyer
3. Time how much it takes to react

• Record your data
• Re-do step 1 to 6 five times

1. Re-do step 1 to 7 with 0, 40, 60, 80 degrees Celsius
2. Re-do step 1 to 8 with coke
3. Clean the desk where you did the experiment

Variables:

Regarding the variables, in this experiment, the temperature of the liquids is the independent variable because it is the factor that is changing to measure the time to react and analyze if it affects the rate of reaction. Then, the rate of reaction is the dependant variable because it relies on the temperature of the liquid, and finally, the volume of 100.0 mL ±      and the number of Mentos (1) put in the liquid are the controlled variables.

Information:

Temperature: 0, 25, 40, 60 and 80 degrees Celsius  ±

Volume in each Erlenmeyer: 100.0 mL ±

Number of Mentos put in each reaction: 1

Data analysis:

Table 1: Data collected with 1 Mentos drooped into 100 mL of Diet Coke

Table 2: Data collected with 1 Mentos drooped into 100 mL of coke

Table 3: Comparison of the average rate of reaction between Coke and Diet Coke with the same volume at different temperature

Graph:

Graph 1: Reaction’s average time based on the temperature of the Diet Coke

Graph 2: Reaction’s average time based on the temperature of the coke

Calculations:

Need to go to the lab to collect the uncertainties of different instruments used

Analysis:

The data collected from the experiment indicates that the reaction time becomes shorter as the temperature increases. Increased temperature increases the mobility of the particles involved in the reaction. Therefore, the rate of interaction becomes higher, facilitating the fast nature of the reaction. This fact becomes evident when increasing the temperature results in the chemicals taking less time to react.

There are different rates of reaction when coke is used, and when diet coke is used. These differences in reaction time occur because of the presence of aspartame in diet coke. Regular coke contains syrup that gives flavor to the drink. Diet coke, on the other hand, does not have any calories because it contains aspartame as the substitute for the sugar components in regular coke. Aspartame dramatically lowers the surface tension of the liquid resulting in a much quicker and more intense chemical reaction. Aspartame acts as a surfactant to the reaction, therefore reducing the time taken for the reaction to occur.

The results obtained from the lab show some degree of accuracy and precision, although the accuracy is not 100%. Different variables affect the different outcomes of the experiment. The average reaction time for regular coke was 2.1 seconds at 0 degrees, and reduced to 1.1 seconds at 80 degrees. In comparison, diet cokes showed reduced reaction times. At 0 degrees, the reaction time was 1.7 seconds and decreased to 0.6 seconds when the temperature increased to 80 degrees. These figures show significant differences in the reaction rates exhibited by the two types of coke.

The experiment was subject to some errors due to different factors. First, the test utilized a mobile phone for recording time. The fact that a human being managed the timing exercise meant that there would be some gaps between the actual values and those that I recorded. These differences may result in obtaining inaccurate values when recording the time taken for the reactions to take place.

The Erlenmeyer may have let out some gas during the setting up of the experiment affecting the reactivity of the system. The reaction involves carbon IV oxide reacting with other carbon dioxide molecules resulting in the eruption. Therefore, when the gas escapes the system, the amount of reactants is significantly reduced. This fact would result in reduced reactivity of the system, leading to erroneous results.

While transferring the components of the reaction, it was essential to avoid holding the container holding the liquid. The human body temperature is about 36.5 degrees, and holding the containers would increase the temperature of the liquid. This action would affect the legitimacy of the results, especially when dealing with temperatures that fall below the human body temperature.

The cleanliness of the equipment is essential to ensure that the contents of the experiment do not get contamination. Contamination of thee components may result in other reactions that reduce the quantity of the reactive material. Therefore, cleanliness is necessary to ensure that the experiment yields accurate results.

The reactions made use of one Mentos in each experimental set. However, different Mentos could not have the same mass. Therefore, the experiments were not subject to the same quantity of reactants. These differences in mass affected the outcome of the test by creating variations in the reaction rates. The results would have been more accurate if the weight of the Mentos was measured and kept constant across all the trials.

The quantity of coke in each experiment may not have been precisely uniform. Some drops of the coke may adhere to the equipment during transfer. Therefore, the amount of liquid available for the different trials was not uniform. These disparities, as minimal as they may appear, affected the reactivity observed in the various experiments. As a result, the values obtained may not have been entirely accurate.

The thermometer used for the experiment may have been faulty. As a result, the temperature readings may have been erroneous. However, it is unlikely that this scenario had a considerable impact on the final results. The same thermometer served for all the experiments, and it could detect rises in temperature. Therefore, the rates of reaction were recorded at different temperatures, which increased gradually at various points.

The reaction that results in the release of carbon dioxide and, with it, relies on the formation of bubbles in the mixture. The surface tension of any given liquid determines the liquid’s ability to form bubbles and the ease with which it creates the bubbles. Therefore, liquids with higher surface tension are less likely to form bubbles and vice versa. There are chemical substances that can reduce the surface tension of liquids. These substances are called surfactants. Diet coke contains aspartame, which is a stable surfactant. It reduces the surface tension of the liquid in the experiment, allowing the rapid formation of bubbles in the liquid. As a result, the release of carbon dioxide from the liquid is fast, signifying the high reactivity of the mixture.

Chemical reactions depend on the interactions between molecules of the reactants. An increase in temperature increases the kinetic energy of the units within the system, thus increasing the frequency at which the particles come together. This reaction that results in the release of carbon dioxide is a physical reaction that involves the interaction between carbon dioxide within the system. The role of Mentos is to break down the chemical bonds between carbon dioxide and the coke, thanks to its rough surface. The rough surface is not visible with the naked eye because, at first glance, the Mentos appears smooth. However, when observed under a microscope, the rough surface of the Mentos becomes visible.

After the breakdown of chemical bonds within the coke is complete, the carbon dioxide is free to interact with more carbon dioxide. This reaction is a physical one that results in nucleation as carbon dioxide escapes from the liquid. Nucleation is the formation of bubbles and is the determinant of how much carbon dioxide escapes from the mixture. The creation of these bubbles depends on the surface tension of the liquid in question. Aspartame from diet coke reduces the surface tension of the liquid, making the formation of carbon dioxide bubbles faster and easier. This property makes the reaction using diet coke faster than when using regular coke.

Therefore, the primary sources of differences in the reaction times obtained throughout the experiment were temperature changes and surface tension. These two factors affected the rate of carbon dioxide production from the liquids. This information is useful when demonstrating the expulsion of fluid from the mixture. Increasing the temperature while reducing the surface tension of the liquids yields the fastest and most reliable reaction. As carbon dioxide escapes, there Is pressure build, which leads to the expulsion of the liquid components in the mixture. The best demonstration of this expulsion would require experimenting with high temperatures while using diet coke to get a liquid with low surface tension. The combination of these two conditions will result in the formation of a geyser similar to that of a volcano experiment. Monitoring these factors is critical in ensuring that the test is successful.

The results of the experiment concurred with my initial expectations, which dictate that the differences in temperature would affect the rate of reaction. The differences in the composition of the two brands of coke also played a role in impacting the rate at which the reaction took place. This realization raises questions on the safety of consuming diet coke and the possible effects that the product may have on an individual’s health.

With all other variables kept constant, aspartame determines the rate at which the reaction occurs. From the experiment, the rate at which the respective reactions (diet coke and regular coke) took place increased was very similar. The difference in the time taken to react at 0 degrees and that of 80 degrees was approximately one second. The little discrepancies seen were perhaps due to the possible errors that may have affected the relationship.

Conclusion:

The experiment confirmed that the temperature of the mixture affected the rate at which the compounds interacted. For any chemical reaction to occur, the particles of the reactants have to interact with each other. High temperatures increase the excitability of particles, increasing the rate at which the particles interact with each other. Therefore, the reaction will occur much faster than when carried out under lower temperatures. Consequently, temperature plays a role in affecting the rate at which the coke reacts with the Mentos.

Reference:

I will add the text I used for the final draft because I have to check if they are reliable.