General Chemistry Laboratory: Soaps And Detergents
None of the oils (olive or vegetable) or fats (lard or shortening) were soluble in water, hydrochloric acid, or sodium hydroxide. In other words, when the oils and fats were mixed with water, hydrochloric acid or sodium hydroxide they did not form a homogenous mixture, proving that all these substances were non-polar. In other words, both oils were able to mix in ethanol because the solution itself is a mixture of non-polar and polar bonds, which allowed the non-polar oils to mix homogenously. However, both fats should have been soluble in ethanol, because they consist of long, non-polar hydrocarbon chains and therefore should have been highly soluble in unpolar solvents like ethanol. Leading me to conclude, that there were a few errors in our methods of testing, and that we could have put too much of the solutes in our solvents. After the solubility tests were performed on the oils and fats, four soaps and two detergents were synthesized with the wastewaters being kept for desirable traits.
To determine which soap or detergent would be environmentally friendly each wastewater was tested for its initial pH level using litmus paper which turned blue when the solution was basic and bright red when the solution was acidic. All the wastewaters of the four soaps were basic, while the two detergents were acidic. To ensure that the wastewater had the least amount of impact on the environment, the pH had to be close to neutral as possible using a process called neutralization.
Neutralization is the process of an acid and a base reacting to form a salt that is made up of equal weights of the acid and base. To determine the amount of acid or base to add to each solution to get its pH equivalent to neutral the titration method was used. After the titration of detergent one it was determined that 25. 8 mLof 1M of NaOH needed to be added to neutralize it. However, detergent two was very different, needing only 8 mL of 1M NaOH to raise its pH level to equivalency. This could have been because detergent one had a higher amount of tap water mixed with its 5 mL of acidic wastewater. Considering that each soap was very basic, the amount of 1M HCl that was added varied. 6. 5 mL of 1M HCl is needed to be added to the soap synthesized with olive oil to reduce it pH level to seven. While the soap synthesized with vegetable oil needed 6 mL of 1M HCl to neutralize its solution. The soap that was produced from lard need about 4 mL of 1M HCl, while the soap synthesized from shortening needed about 5. 8 mL of 1M HCl to neutralize the solution to a stable level.
Once the titrations were completed, we looked at each graph to determine which filtrate was most concentrated, meaning it took the most acidic or basic solution to neutralize it. The graphs showed that detergent one was more concentrated taking about 18 mL more of NaOH to reach equivalency point to detergent two. In other words, we concluded that detergent two was environmentally friendlier then detergent one because it required a smaller amount of NaOH to neutralize its pH meaning it would have a significantly smaller impact on the environments pH.
The soap with the highest concentration was olive oil, however between the four soaps there was not a big jump like there was between the detergents. As a result, we concluded that the soap that would have the least amount of impact on the environments pH would have been lard, only needing 4mL of HCl to neutralize itself. In our solubility test, we found that none of the soaps or detergents were soluble in any of the solutions (HCl, NaOH, Water, and Acetone). However, an important factor to realize is that soaps are made from long hydrocarbon chains which are non-polar and hydrophobic (repelled by water) and salt at the end of the soap molecule which is ionic and hydrophilic (water soluble). In fact, the type of fatty acid and length of the carbon chain determines the properties various soaps will have. Fatty acids, such as lard and shortening give mainly sodium stearate a very hard, insoluble soap. For this reason, the lard and shortening synthesized soap were not soluble in any of the solutions, proving to still be non-polar. However, while olive and vegetable oil are a source of sodium laurate, a very soft soluble soap, they were not soluble in any of the solutions as well.
We expected olive and vegetable oil to be soluble in acetone because acetone is an alcohol like ethanol. Leading me to conclude that errors such as, methods used to carry out our solubility tests and putting too much soap into our solvents could have caused errors in our results. In our cleaning ability test, we found that lard and shortening were the most effective in cleaning the lard off the watch glass, while the detergents were least effective. Soaps are excellent cleaners because of their abilities to act as an emulsifying agent. In other words, it means that while oil (which attracts dirt) doesn't naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed. While detergents are an effective cleaning product because they contain one or more surfactants, their chemical makeup can be arranged to perform well under a variety of conditions which could be the reason they did not perform well. These results helped support our conclusion that lard was the best soap because not only was it environmentally friendly, but it was also a very effective cleaner.
In the lather-ability test, we found it difficult to determine which soap or detergent produced the most bubbles. However, from my observations the detergents and vegetable oil initially produced the most bubbles, but over time, olive oil was able to retain most of the bubbles while the others faded with time. Lard and shortening however, produced the least amount of bubbles. The bubbles formed in this experiment were caused by water being added to the soaps and detergents which caused their hydrophobic ends to move to the surface and repel each other, causing the water molecules to then separate from each other, lowering the surface tension allowing bubbles to form.
