Humans have been practicing pain management for thousands of years. People in the stone age believed that pain and diseases were punishments from the gods, and their way of treating the pain was by praying, proposing religious offerings, and sacrificing animals. At around 400 BC, there was a very common pain reliever called willow bark. People would chew on the bark to reduce fever and inflammation. The bark of the willow extract contains salicin, a chemical similar to aspirin (L, 2014). Salicin is believed to be responsible for the pain relieving and anti inflammatory effects of the herb. In fact during the 1800’s, scientists began synthesizing active compounds from willow to make aspirin. Identifying the active ingredients in willow bark was a formidable task. With the hundreds of chemicals contained in the bark, it was almost impossible to purify the single chemical capable of relieving pain and fever, alongside when the chemists had no computers or equipment to use that the humans in the 21st century have. Another relative substance is the wintergreen leaf, which is used for pain relief. When the wintergreen leaf is steamed in water, the enzymes within the leaf called methyl salicylates are released. This chemical relates with aspirin and willow bark, as they all relieve headaches, nerve pain, and contain a similar enzyme. How does aspirin work? Aspirin utilizes a central process in the body by blocking the production of prostaglandins. When body tissue is infected or damaged, the prostaglandins hormones will create a healing process of the reactions that cause the fever, pain, and inflammation. Prostaglandins are hormones created during a chemical reaction in the general area where an injury has occurred. Prostaglandins are derived from fatty acids in the cell membrane. These fatty acids are cut off of a membrane lipids by an enzyme known as phospholipase A2. Afterwards, an enzyme called cyclooxygenase creates a ring in the fatty acid and adds some oxygens to form an intermediate prostaglandin, with a diversity of functions. These functions include acting on the hypothalamus to increase body temperature, stimulating immune cells in inflammation, and sensitizing nerves to pain, as well as initiating clotting in blood, constricting and dilating blood vessels, producing mucus in the stomach to protect the stomach lining from stomach acid, and much more functions (Mary, 2015). What aspirin does is that it stops cyclooxygenase from working, which blocks prostaglandin synthesis and results in temporary reduction of prostaglandin induced pain, fever, and inflammation until cyclooxygenase activity returns to normal. Aspirin is not the only drug that works by inhibiting cyclooxygenase. Other common drugs such as ibuprofen, acetaminophen and naproxen also inhibit cyclooxygenase and have similar effects as aspirin. (Burnningham, 2016) Since prostaglandins are not just involved in discomfort, using aspirin also stops other body functions as well. One of the prostaglandins that aspirin prevents from synthesizing is thromboxane A2, which is involved in activating platelets to initiate blood clotting. By taking a low dose of aspirin every day, it will become harder for blood to clot. This is useful in preventing diseases caused by blood clots such as heart attacks and stroke, and low dose aspirin is recommended for older aged people who have a higher risk of suffering from those diseases. Aside from this benefit, aspirin does contain some drawbacks as a pain reliever. Aspirin also decreases production of protective mucus in the stomach where stomach acid can potentially burn through the stomach, leading to gastric ulcers and internal bleeding. This can occur when the stomach’s acidity is increased significantly, if aspirin is taken regularly since its active ingredient is salicylic acid which is an acid. Another possible drawback is the worsening of asthma. Another family of fat based molecules called leukotrienes can also be formed from the fatty acids split by phospholipase A2. These leukotrienes cause narrowing of airways and more mucus production, making breathing difficult. When cyclooxygenase is inhibited, there are more fatty acids available to be converted into leukotrienes, which sometimes causes the symptoms of asthma worse (Blaine, 2015). Taking aspirin is safe when taken occasionally. Too much aspirin can lower the pH in your stomach which can result in dangerous symptoms. The stomach contains gastric juice which is a mixture of mucus, hydrochloric acid, and digestive enzymes. This stomach juice is what promotes digestion of food in humans. Since the stomach has strong HCl acid, it can almost complete ionization in water. The mucus in the stomach spreads across the lining of the stomach with a thick barrier that is acid and enzyme resistant. This stomach mucus is very rich in bicarbonate ions that are used to neutralize the pH of stomach acid, but too much aspirin will reduce the mucus as stated before, allowing the acidity to rise. The german pharmacist and chemist Felix Hoffman came up with an idea to get rid of the irritating stomach effect that would make the drug more tolerable to the stomach . Felix successfully created a new pill that could prevent stomach irritation and called it “Aspirin”. All Hoffman did was find the solution for the original pill and acetylated salicylic acid, replacing the hydroxyl group with an acetyl group (Sheryl, 2016). Although aspirin was finalized, many people had sensitive stomachs where taking an aspirin may still cause stomach irritations so two other types of aspirin were made. Enteric aspirin was made so the pill would not digest in the stomach but in the small intestines. The enteric aspirin is coated with fatty acids, waxes, plastics, and plant fibers, which allow the pill to pass through the stomach and into the small intestines without getting dissolved. The small intestines has a lower acidity than the stomach acid so the enteric aspirin would take longer to be absorbed at a slower rate. Enteric aspirin would not be effective for common flu’s or colds, but would be for long term illness’. Buffered aspirin was made to reduce the acidity in the stomach to a neutral point where the aspirin can dissolve without complications. The buffered aspirin contains an antacid (calcium carbonate) that will react with the stomach HCl acid and proceed into a neutralization reaction where the aspirin will be reacted with a buffered solution at a lowered pH and dissolved. In the lab experiment buffered, enteric, and normal aspirin were dissolved in a 0.1 concentration of HCl solution, and sodium bicarbonate solution. Each pill was tested to compare the dissolution in both solutions. The HCl solution would represent the stomach acid, and the sodium bicarbonate solution would represent the small intestines in comparison of acidity levels. An environmental buffer example is acid rain and lakes (refer to Appendix B: Figure 1). With the presence of particular rocks surrounding a lake that contain calcium carbonate, the lake can be protected from pollution of incremental acidity. Limestone is a familiar form of calcium carbonate (CaCO3). The acids in acid rain promote the dissolution of calcium carbonate when raining overtop a lake by reacting with the carbonate anion, resulting in a solution of bicarbonate. Since the surface waters are in equilibrium with atmospheric carbon dioxide, there is a constant concentration of carbonic acid (H2CO3) in the water. The presence of limestone and other calcium carbonate rock in lakes and streams helps to maintain a constant pH because the minerals react with the excess acid. However, acid rain eventually can overcome the buffering capacity of the surface water. (Howe, 2012) The purpose of this lab is to determine which type of aspirin is most effective on humans in a safe . If any type of aspirin trial has a close to neutral pH level and small dissolution time it would be considered the most effective and safe because the faster bodily absorption of medication will result in quicker effects to treat the illness, and the more neutral acidity level would be safer for humans to avoid over acidic complications in the body. Methods A total of six 100 mL beakers and one 125 mL erlenmeyer flask were completely washed with tap water and then rinsed off with distilled water. 60 mL of distilled water was given to three of the six beakers along with 6 mL of HCL with 1M. The erlenmeyer flask was filled with approximately 60 mL of distilled water and then added with 0.71 grams of baking soda. The resulting solution after stirring filled the last three beakers with 20 mL of solution in each using the pipette mechanism. Litmus paper was then used to record the pH of all six beakers. Three distinct types of aspirin tablets were obtained with only two of each tablet. The buffered aspirin tablet was divided into halves from originally one tablet. Three different tablets were placed into the beakers containing the HCl solution, and the other three different tablets were placed into the beakers containing the sodium bicarbonate solution. A timer was set to record the time until the tablets stopped dissolving. The pH of all six beakers were recorded after the times were completed. Results For quantitative and qualitative lab data, pH levels before and after, and timing for all trials in both solutions refer to Appendix A: Table 1, and Table 2. Analysis An outlook of the general statistics from the data observed. The acidity of the pills did not make any significant changes before and after dissolving in both hydrochloric acid and sodium bicarbonate solutions (refer to Appendix A). The solution with the fastest time to dissolve the pills was sodium bicarbonate (refer to Appendix A: Table 2). Not all of the pills dissolved completely in both solutions. The regular aspirin seemed to have the fastest dissolution time in both solutions, being the fastest in sodium bicarbonate with a time of three minutes and seven seconds (refer to Appendix A: Table 2). The buffered aspirin in both solutions stayed at a constant pH level throughout the reaction (refer to Appendix A). The regular aspirin and buffered aspirin both consisted large amounts of bubbles throughout reacting in both solutions while the enteric aspirin consisted of small amounts of bubbles (refer to Appendix A). The enteric aspirin in general did not dissolve well and had taken long to dissolve in both solutions (refer to Appendix A).Discussion The regular aspirin reacted well in both solutions as expected with the fastest times. The regular aspirin did not have any coating or buffer to the pill which allowed the pill to dissolve quicker at higher acidity. The regular aspirin showed more signs of reaction than the other pills because of the large amount of bubbles the solution was producing as well as almost 100% dissolution of the pill in both solutions. The pH of the regular aspirin did not change at all throughout the reaction in the HCl solution which would not make sense since the acidity level of the solutions should go up, decreasing in pH when the active chemicals of the pill are absorbed. A reason why the pH did not go lower than its originally pH before dissolution was because the litmus paper does not read lower than 1 pH, so although the HCl solution assumingly become more acidic, the litmus paper just could not read the acidity. The regular aspirin in the sodium bicarbonate solution made more sense in terms of data collected. The acidity level of the solution had decreased from 8 pH before dissolution to 7 pH after. This was expected from the sodium bicarbonate solution to become more acidic with the regular aspirin pill but not significantly since the sodium bicarbonate solution is a base. Unlike in the HCl solution the regular aspirin pill did not fully dissolve in sodium bicarbonate which is fairly expected since the acidity level in the small intestines is lower than in the stomach. In this trial the active ingredients could have been absorbed before the pill itself which left the pill not completely dissolved. The buffered aspirin pill in the HCl solution had the same pH before and after dissolution, but this is expected because the antacid on the aspirin buffers the solution preventing the acidity of the solution to change once the active chemicals of the pill were absorbed. The buffer could have made the solution stay at 1 pH in this trial. Also having a time of 7 minutes to dissolve in the HCl solution was expected since the acidity should not have changed, making the dissolution slower. This proves that the regular aspirin pill became more acidic because its time to dissolve in the HCl solution was 3.5 minutes, quicker than the buffered pill in the HCl solution. In the sodium bicarbonate solution the buffered aspirin had a constant pH of 8 before and after dissolution. As expected, the antacid of the pill buffered the solution to prevent the pH to change. Aside from the pH, the top half of the pill was only dissolved. This could mean that either the antacid was ignored and only the active chemicals of the pill were absorbed since the time of the dissolution was fast with 3 minutes, but that would not make sense because the solution did not change in acidity, or the buffer was only absorbed and the pill itself malfunctioned, or that half that was dissolved consisted of half antacid and half active chemicals of the pill. This would mean the solution was buffered and also absorbed active chemicals of the pill but only a small portion of each which made the dissolution quicker than normal at 3 minutes. The enteric aspirin in the HCl solution did not dissolve at all and took the long with a time of 27 minutes. This was expected since the the enteric aspirin was not designed to dissolved in the stomach. Only the outer coating of the pill had small decay but no dissolution. The pH of the solution stayed consisted at 1 pH before and after, most likely did not go any more acidic since the solution did not make contact with the active chemicals. The enteric aspirin in the sodium bicarbonate solution took the longest to dissolve at 35 minutes. Considering that the small intestines breaks down foods slower than the stomach this makes sense. Also the solution in this trial had absorbed the active chemicals in the pill unlike in the HCl solution, which got the pH to change from 8 pH before to 7 pH after. In this trial the entire pill was dissolved. The hypothesis states that the most effective pill would have the fastest time, and the safest pill would have the lower acidity to be more neutral. With that stated, the trial that was most effective in terms of safe and fast was the buffered aspirin in the small intestines. This trial was one of the fastest times and had the highest pH close to neutral. Although, this aspirin could not be dissolved in the small intestines without getting dissolved in the stomach first. So really each pill is effective but in different circumstances.An issue with the lab was that the litmus paper was unable to read any more acidity than a pH of 1. This way the aspirin pills could be determined more accurately for effectiveness or if the pills did not work in the solutions. Perhaps with the help of a pH meter the acidity of the solutions could be determined accurately.Another issue with the lab was that the pills could have been roughed up with before getting put into solution. Roughed up meaning from the point of taking out of the package to the point of dissolving into the solution. The buffered aspirin could have lost some antacid due to bumps and rubbing on the counter or any surface in general. Losing antacid would result in a more acidic solution and misinterpretation of results. Also with the enteric aspirin, the exterior preventing the pill to dissolve in the stomach acid could have been broken open before being placed into the solutions, in result potentially getting the active chemicals in the pill to be absorbed in the stomach.An extension to the lab could be to test the aspirin pills in titration trials. Determining how much solution of HCl or sodium bicarbonate it would take to dissolve the pills and compare to human stomachs and small intestines to visualise the amount of acidity and volume needed. As well as using the pH meter to measure accurately acidity levels.