Discussion and Scientific explanation
The goal of this experiment was to synthesize multiple soaps and detergents using different starting materials and methods to then determine which one had the most desirable qualities for the environmental group.
The three starting materials used were shortening, lard, and vegetable oil. Each of these materials first went through a solubility test, which found that all three were a nonpolar material (Cooper) as shown in Table 1. From there the soaps was made by taking the starting material and adding glycerol to turn it into a triglyceride. After this was done, NaCl was added which would then finish the process of making the soaps. The importance of adding the NaCl is that when added it gives the soap hydrophilic and hydrophobic ends (Cooper). These are desirable qualities for the soap, because when the soap is mixed with water and oil the hydrophilic ends bind to the water, while the hydrophobic ends bind to the which allows it to be carried away when in the process of cleaning(Chagrin Valley). Another important part of the soaps structure, is that there is an O- Na+ group attached to the carbon. This end is what makes soap basic because when soap is mixed with water, it forms OH- ions, which is a property of a base (Infoplease). The process for making the detergents was different as the starting material for each was a lauryl alcohol which would then have NaOH added to it to produce a Sodium lauryl sulfate. Like soaps, detergents also have hydrophilic and hydrophobic ends that allow it to bind to oil and water (Cooper).
The solubility tests for every soap and detergent showed that they were all nonpolar as shown in table, just like in the first solubility test. Table 2
To test the cleaning qualities of the every soap and detergent they were tested for their cleaning-ability and lather-ability. For the cleaning-ability test .1 g of shortening was spread on a watch glass for each trial, which was then cleaned by one of the soaps or detergents. The soap made from shortening was the best soap at cleaning, while the detergent made from method 2 was the best at cleaning out of the two as shown in Table. This is important because if the soap or detergent is not effective, then it is not worth it to produce that soap or detergent. Next, was the lather-ability test which involved putting a bit of every soap and detergent in individual test tubes with a little bit of water. From there, the test tubes were shaken up to see which one produced the most bubbles. The results were the same for this test as the soap made from shortening and the detergent made from method 2 produced the best results shown in Table 3. Lather ability is important for both soaps and detergents. It shows if a soap or detergent will be effective at cleaning. When the soap or detergent is introduced to water and friction, it starts to form bubbles. These bubbles are effective at trapping dirt molecules and removing them from the surface (LiveStrong). If a lot of these bubbles form, then there is a greater chance that it will clean the surface, which it was applied to. Thus the results from both the cleaning and lather ability test indicate that method 2 detergent would be the most effective at cleaning.
The wastewaters from both detergents and the soap made from vegetable oil were titrated to analyze the impact that they would have on the environment. Each wastewater was put through a ph test initially to see what titrant would be used. The vegetable oil wastewater was basic, which meant that HCl would be used for the titration. The amount of titrant used to neutralize the soap is shown in Graph 1. The first titration has some error because this wastewater was mixed with a little bit of the wastewater from the other soaps. Both of the detergents’ wastewaters were found to be acidic. This meant that NaOH was gonna be used as the titrant. The amount of titrant used to neutralize these wastewaters is shown in Graph 2 for method 1 and Graph 3 for method 2. The results from these tests are important because if wastewater with high or low ph entered the environment it could throw off the ph of the water in the surrounding area affecting the ecosystem.
The next test was to run a solubility test with the shortening soap and method 2 detergent in both pond water and well water. Each one was placed in several individual test tubes filled with either pond water, or well water to see if they were soluble in it. As shown in Table 4 both the soap and the detergent were not soluble in the waters. To figure out why this was happening, a cation test was done to see if there were in ions in the water that would make it hard. This works because when the sample is heated it causes an electron to go to a high energy level where it then drops back down to the lower levels, where it releases light. This light then has a color, which correlates to different elements (Cooper). The results of the test are shown in Table 6. It was determined the pond water contained Magnesium, while the well water contained Calcium. These results were backed by the fact that calcium and magnesium ions make water hard (The Spruce). This explains why the soaps weren’t soluble in the pond and well water; because soaps and detergents have a hard time bonding with hard water (The Spruce). Instead, they bond with the magnesium and calcium ions to form soap scum (The Spruce). Another test that was done to figure out why both the soap and detergent was not soluble in the water samples was a Ph test. A Ph test would help with this since it is known that soaps and detergents do not work well in acidic water (Chemical Technology). The results were shown in Table 6 and confirm that both waters being acidic which explains why the soap and detergent were not soluble in the water samples. To fix this EDTA was added to both the pond water and the well water. The EDTA is effective at fixing this problem because it bonds to the calcium and magnesium ions, which then allows the soap or detergent to bond with the water (Webmd). This is confirmed by the results in Table 5, which shows that both the soap and detergent were partially soluble in both samples of water.
The last test that was done was to have both the soap and detergent clean oil off of a piece of shirt to determine which one out of the two was most effective at cleaning oil. This test was done by adding one drop of olive oil to the shirt and cleaning it with the soap, and then repeating it again but with the detergent. The results were shown in Table 7 and it was found that the Method 2 detergent was the best at cleaning the oil off of the piece of shirt.
At the conclusion of all these tests, it was decided that Method 2 detergent was the best option for the environmental group. This is because it outperformed the other detergent in the cleaning and lather ability test, as well as the shortening soap during the oily shirt test. Another way it outperformed the other soap, is that it took less titrant to neutralize the wastewater from method 2 detergent, which makes it more cost effective than the soap.