1.0: ABSTRACT
This experiment is conducted to achieve the objectives that are to prepare soap from mineral oil and to study and compare the properties of soap and synthetic detergent. Besides, the other objectives are to compare the cleaning abilities of soap and detergent in cleaning stain on cloth strips and to determine the relative cleanliness of soap and detergent through visual observation. The properties that are compared in this experiment between soap and detergent are precipitation, emulsification and cleaning abilities. This experiment consists of three parts that are for preparation of soap, comparison for emulsification and precipitation and also comparison of cleaning abilities for both of them. Part A for this experiment which is preparation of soap is conducted by mixing ethanol, vegetable oil and sodium hydroxide (NaOH) solution. The chemical reaction of preparation of soap is known as saponification. Soaps are sodium or potassium fatty acids salts, produced from the hydrolysis of fats in the saponification reaction. The mass of soap obtained from part A of this experiment is recorded. While part B of this experiment, the pH for both soap and detergent is taken and the properties of emulsification and precipitation is done using the mineral oil and 1% of CaCI2, MgCI2, and FeCI3 solution. An emulsifier is capable to disperse one liquid into another immiscible liquid. The formation of single layer and precipitation is observed. For part C, the cloth strips that have been soaked in tomato sauce is used to compare the cleaning abilities of soap and detergent. The ability of cleaning of soap and detergent is determined based on the clean of cloth strip when the soap and detergent solution containing cloth strips is stirred for five minutes. Hence, the result from this experiment is obtained. For part A, the mass of soap recovered is 23.029 g. The pH of the soap solution is 11.58 while the pH of detergent solution is 8.92. The emulsification occurs in detergent while the precipitation occur in soap. 8 drops of 1 M hydrochloric (HCL) solution for soap solution and 1 drop of 1 M hydrochloric (HCL) solution are needed to have the pH of three of the solutions. The detergent can clean faster than soap.
2.0: INTRODUCTION
The soap and detergent is used in the daily life. Soaps are the sodium and potassium salt of long chain fatty acids that are generally made by alkaline hydrolysis reaction. It is a product for cleaning made from natural ingredients that may include both plant and animal products, including items such as animal fat ( tallow) or vegetable oil ( olive oil). They come in a variety of shapes, sizes, and colors, and it seems that each is used for a specific purpose. While detergent is organic sulfonic and phosphoric acid salts and it ia s product to promote the development of detergency. General overall hydrolysis reaction of soap is as shown below: fat + NaOH → glycerol + sodium salt of fatty acid
(Equation 2.1) The history have revealed evidence that Babylonians were making soap around 2800 B.C. Babylonians were the first one to master in the art of soap making from fats boiled with ashes. For at least 5000years ago, soap was used in cleaning wool and cotton used in textile manufacture and was used medicinally. Fatty acids that produced from the reaction of oil (triglyceride) with sodium hydroxide are straight chain monocarboxylic acids. The bonds between the carbons in saturated fatty acids are all single bonds, while unsaturated fatty acids have one or more double bonds in their chains. The size fatty acid are usually in the range of 10-20 carbons. While oil (triglyceride) consist of a three-membered carbon chain (glycerol backbone) with a fatty acid bonded to each of the three carbon atoms in the glycerol backbone (ester linkage). The ester linkage is broken to form glycerol and soap in the saponification process. The sodium chloride addition is for soap precipitation once the saponification process complete. Vacuum distillation is used to draw off the water from the mixture and then, the soap is recovered.
The first detergent has been produced during World War 1 due to the argue to find the other cleaning agent that can clean in hard water. Nowadays, there are many kinds of detergent that generally contain surfactants, builder and other additives such as bleaching agents and enzymes. The use of builders are to remove calcium and magnesium ions in hard water the surfactants are for cleaning properties. However, the detergents that contains phosphates are not safe to be used. It will give impacts to wastewater and cause excessive growth of aquatic plants. Then, it will result the depletion of oxygen in aquatic environment that may interfere the fish and aquatic plant growth.
3.0: OBJECTIVES
1. To prepare soap using mineral oil 2. To study and compare the properties p roperties of soap and synthetic detergent 3. To compare the cleaning abilities of soap and an d detergent in cleaning stain on cloth strips 4. To determine the relative cleanliness of soap and detergent through visual observation
4.0: THEORY
This experiment is conducted to prepare the soap and compare the properties of soap and detergent solution which are precipitation and emulsification. The cleanliness of soap and detergent is also investigated in the experiment. S oap is prepared by saponification reaction which is the reaction of sodium or potassium hydroxide with triglycerides to produce gl ycerol and soap, a fatty acid salt (source: http://chemistry.about.com/library/glossary/bldef825.htm http://chemistry.about.com/library/glossary/bldef825.htm)). Triglycerides used in this experiment is vegetable oil. Thus, soap is the sodium salt of a long chain fatty acid that usually contain 12 to 18 carbon atoms which can be expressed as term R.
Figure 4.1: Triglyceride Sodium salt of lauric acid produced when vegetable oil of triglycerides group is used. used. The figure 4.2 shows the formation of sodium laurate:
Figure 4.2: sodium laurate formation
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Soap molecule consists of highly polar end (the ionic group COO ) and long non polar tail (the hydrocarbon chain of the fatty acid). acid ). Each of the structure have its own functions. The polar end of the molecule which is known as hydrophilic tail can dissolve in water molecules. The non-polar end can dissolve d issolve the grease and dirt and it is called hydrophobic tail.
Figure 4.3: the polar end of soap molecule The soap is working as cleaning agent by suspending the dirt or oil within its structure (source: http://www.slideshare.net/jenniferpratt03/SaponificationPresentation http://www.slideshare.net/jenniferpratt03/SaponificationPresentation)). Besides, soap is also a wetting agent that can reduce the surface tension of water by allowing the water molecules to encounter the dirt. The dirt consists of oil along with the other organic species. Thus, the the soap is also known as emulsifying agent. Water is a polar species while the organic compound are nonpolar. This difference cause the substances cannot dissolve in each other. The negatively charge heads of the soap molecules cause the forming of a spherical shape called micelle. They orientate themselves where the hydrophilic tail is facing the water and the non-polar tails rearrange towards the center of the micelle. The non-polar head will interact with oil and gather it to the center of the micelle. Hence, the dirt and micelle is washed away when rinsed with water. The acidic water is known as hard water because it contains highly concentrated magnesium and calcium ions (source: http://chemistry.about.com/od/howthingsworkfaqs/ http://chemistry.about.com/od/howthingsworkfaqs/aa/ softwaterrinse.htm). These ions will form insoluble fats known as scum that will result the inability of the soap as cleaning agent. So that , the detergent is developed to encounter this problems. The difference between soap and detergent is detergent has different structure known as sulfonate end. The synthetic detergent formed micelles is released into rivers and lakes cause explosive growth of algae in aquatic environment.
5.0: APPARATUS
pH meter
Test tubes with rack
Cloth strips
Beakers
Filter paper
Erlenmeyer flask
Measuring cylinder
Stirring rod
Buchner funnel
Aspirator
Electrical balance
Vacuum filtration
MATERIALS
Stock soap solution
Stock synthetic detergent (Dynamo)
Distilled water
CaCl2 solution
MgCl2 solution
FeCl2 solution
Tomato sauce
Mineral oil
1M HCL solution
Ethanol
6 M NaOH solution
Vegetable oil
6.0: PROCEDURE A. Soap preparation
1. 12.5 mL of vegetable oil is placed in a 250 mL Erlenmeyer flask. 10 mL of ethanol and 12.5 mL of 6M sodium hydroxide solution are added to the flask. The mixture is stirred using a stirring rod to mix the contents con tents of the flask. Note: carefully smell the alcohol by wafting it towards your nose. 2. The 250 mL flask is heated in a 600 mL boiling water bath. 3. The mixture is stirred continuously during the heating process to prevent th e mixture from foaming. If the mixture should foam to the p oint of nearly overflowing, the flask is removed from the boiling water bath until the foa ming subsides, then heating is continued. The mixture is heated for 20-30 20 -30 minutes or until the alcohol odor od or is no longer detectable. 4. The paste-like mixture is removed from the water bath a nd the flask is cooled in an ice bath for 10-15 minutes. 5. While the flask is cooling, the vacuum filtration apparatus is set up as shown in Figure 6.1.. The vacuum flask is secured to a ring stand with a utility clamp to prevent prev ent the apparatus from toppling over.
Figure 6.1: Vacuum filtration apparatus
6. A piece of filter paper is weighed to the nearest 0.001g and the mass is recorded. The filter paper is placed inside the Buchner funnel. T he paper is moistened with water so that it fits flush in the bottom of the funnel. 7. Once the flask has cooled, 75 m L of saturated sodium chloride (NaCl) solution is added to the flask to “salt out” the soap. 8. The water is slowly turned on at the aspirator. The mixture is poured from the flask into the Buchner funnel. Once all of o f the liquid has filtered through the funnel, t he soap is washed with 10 mL of ice-cold water. The suction filtration is continued until all of the water is removed from the soap. 9. The soap is removed from the funnel and a nd it is pressed between two paper pape r towels to dry it. The filter paper and dried soap are weighed, then the mass is recorded to the nearest 0.001g. The mass of soap is determined d etermined by difference and the mass of the soap is recorded.
B. Comparison of Soap And Detergent Properties-Precipitation And Emulsification
1. A stock soap solution is prepared by dissolving 2g of prepared soap in 100 mL of boiling, distilled water. The mixture is stirred until the soap has dissolved and the solution is allowed to cool. 2. Step 2 is repeated using 2g of synthetic detergent. The pH of each solution is determined using pH meter when both solutions are cooled. 3. Three test tubes are labeled as test tube 1, 2 and 3. 4 drops of mineral oil are added to each test tube. 5 mL of distilled water is added to test tube 1, 5 mL of stock soap solution is added to test tube 2 and 5 mL stock synthetic detergent is added to test tube 3. 4. Each of the solution is mixed by shaking and stands for three to five minutes. The solution that emulsifies the oil by forming a single layer is noted. 5. The mixtures are poured into the waste container. The three test tubes are cleaned and dried.
6. Three more test tubes are labeled as test tube 1, 2 and 3. 2 mL of stock solution is placed in each of the test tubes. 2 mL of 1% CaCl 2 solution is added to test tube 1, 2 mL of 1% MgCl2 solution is added to test tube 2 and 2 mL of 1% FeCl2 solution is added to test tube 3. The solutions are mixed by shaking each of the test tubes. The observations are recorded. 7. 4 drops of mineral oil are added to each of the test tubes in step 6. The solutions are mixed by shaking each of the test tubes and the solutions are a re let to stand for three to five minutes. The solution that emulsifies the oil by forming a single la yer is noted. 8. Steps 6 and 7 are repeated repeate d using 2 mL of stock detergent solution. 9. Precipitate solutions and the solution that emulsifies the oil by forming a single layer are noted. 10. Then the mixtures are poured into waste container. The test tubes are cleaned and dried. 11. 5 mL of stock soap solution is placed in cine clean test tube and 5 mL of stock detergent is placed in a second test tube. 1M HCl is added one drop at a time to both solutions until the pH in each test tube is equal to 3 using pH probe. The number of drops of acid added to each mixture is counted. Any An y precipitated solution is observed. 12. 1 drop of mineral oil is added to each test tube in step 11. The solutions are mixed by shaking each of the test tubes. Any oil emulsified is observed.
C. Comparison of The Cleaning Abilities of A Soap And Detergent
1. Three beakers are cleaned, dried and labeled. 20 mL of stock soap solution is placed in the 1st beaker. 20 mL of stock detergent solution in second beaker and 20 mL of a commercial liquid in a third beaker. 2. Three cloth test strips that have been soaked in tomato sauce are obtained and placed one in each of the beakers. The each solution is stirred repeatedly with stirrer rod for 5 minutes. 3. The cloth strips is removed from the soap and detergent solution. The excess water is squeezed out. Each cloth strip is visually compared to determine their relative cleanliness. The observations are recorded.
7.0: RESULT Part A: Soap Preparation
Mass of filter paper (g)
0.563
Mass of filter paper + soap (g)
23.529
Mass of soap recovered (g)
23.029
Part B : Comparison of Soap And Detergent Properties-Precipitation And Emulsification
Brand name of synthetic detergent
Dynamo
pH of soap solution
11.58
pH of synthetic detergent solution
8.92
System
Emulsification occurred
Distilled water
No
Soap
Yes
Detergent
Yes
Hard and acidic
System
Precipitate Soap
Oil emulsified Synthetic
Soap
detergent
Synthetic detergent
CaCl2
White
No
No
Yes
MgCl2
White
No
No
Yes
FeCl2
Brown
No
No
Yes
No
No
Yes
orange Acidic
White
Stock solution
Number of drops
Soap
8
Detergent
1
Part C : Comparison of The Cleaning Abilities of A Soap And Detergent Beaker
Stock soap solution
Observation
It washed slower than detergent. the tomato sauce still remain.
Stock solution
detergent Very clean and it washed faster. No tomato sauce remain.
Relative cleanliness: stock distilled water solution < stock soap solution< stock detergent solution
8.0: CALCULATION
Mass of filter (g)
0.563
Mass of filter paper +
78.806
soap + container (g) Mass
of
soap
23.029
Mass of container (g)
55.214
recovered (g)
Mass of soap recovered recovered . g – . g . g . g = 23.0286 g Mass of filter paper + soap = 0.563 g + 23.029 = 23.592 g
9.0: DISCUSSION
Conjugate bases of the fatty acids are formed in the saponification reaction in the presence of the base. These conjugate base is a proton acceptor from any source including in water. Fatty acid is a carboxylic acid with a long aliphatic chain which is either saturated or unsaturated. Saturated fatty acids are long-chain carboxylic acids that have no double bond while the unsaturated fatty acid has double bond Hard water is known as water that has magnesium and calcium ions. It will interfere the cleaning action of soap due to the formation of precipitation called scum. This scum will leave a deposit on clothes during cleaning action. The first objective is to prepare the soap by the saponification reaction. The mixture is stirred to make sure that all the soap and detergent mix altogether the contents of the flask and to prevent from foaming during heating process. While doing this experiment, the temperature of boiling water bath must be controlled at the optimum temperature to prevent the overflowing of the mixture. It can interfere the preparation preparation of soap process. The ethanol is added in the flask to prepare the soap to harden up the soap while the sodium hydroxide is used for the base-driven hydrolysis of esters (as in saponification). The pH of the soap solution is 11.58 while the pH of the detergent solution is 8.92. The soap is more alkaline than detergent. The other objective is to compare the properties of soap and detergent which are precipitation and emulsification. The result obtained from the experiment is precipitation occur in soap while the emulsification occur in detergent. Based on the theory, the soap is also an emulsifying agent as well. It can be one of the factors that cause the less effective in cleaning action. Besides, the soap form precipitation in CaCl2 solution, MgCl2 solution and FeCl2 solution added The errors had occurred in this experiment. The detergent is better in cleaning action than soap and it is due to the precipitation that does not occur in detergent d etergent solution.
Besides, compare the cleaning abilities of soap and detergent in cleaning stain on cloth strips and to determine the relative cleanliness of soap and detergent are also the objectives in this experiment. Detergent is more effective as cleaning agent than soap. It is also can be effective in both hard and soft water. The tomato sauce still remain on cloth strips that had used the soap solution as cleaning agent while the cloth strip is clean when it is washed by detergent solution. The cleanliness of detergent increases due to the contents of detergent that has one or more surfactants. The surfactants is known as surface active agents that will modify the surface of the liquid and reduce the surface tension. The surface tension is created when the water molecules at the surface are pulled into the body of the water. the higher surface tension will inhibit the cleaning process. Hence, more surfactants can reduce more surface tension and increase the cleaning process.
10.0: CONCLUSION
The soap is prepared and the soap and detergent properties that are emulsification and precipitation is being compared by observations. From this experiment, the soap is not emulsified but based on the theory, the soap acts as emulsifying agent. The abilities of forming precipitations can be seen clearly in soap solution while the detergent did not form precipitation. Besides, the detergent shows the more effective as cleaning agent than the soap. This is due to the magnesium and calcium ions that will form precipitation with soap in hard water. It will cause the less molecules of soap in the solution.
11.0: RECOMMENDATION
There are many ways that can be done to get the more precise and accurate result for this experiment. Firstly, the apparatus should be washed and dried before being used in the experiment. This is due to the prevention p revention of other reagents used in the previous experiment might affects the results obtained. It is also to reduce the impu rities in the experiment. The temperature for part A in this experiment which is preparation of soap should be aware. This is because to prevent overheating and too much foam formed and will cause overflowing of the mixture. The temperature should be at the optimum temperature to get the high quality of soap. The pH of the soap and detergent solution is also should be taken at the same temperature. The other recommended way is by repeating the experiment twice to get the average reading. The average reading is more accurate and more convincing than the result obtained from the experiment. It can overcome the minor error occurred during the experiment is being conducted. Besides, the other recommendation is being focus while observing the changes of the solution. The change of color can be seen clearly by using the white paper as the background. Besides, the preparation of soap can also use the animal fat instead of vegetable oil. Both of them are esters of carboxylic acid and they have a high molecular weight. 12.0: APPENDIX
Figure 12.1: vacuum filtration
13.0: REFERENCE
saponification . (2006, 4 4). Retrieved 6 8, 2013, from slideshare:
http://www.slideshare.net/jenniferpratt03/SaponificationPresentation
saponification. (2013). Retrieved 6 8, 2013, from About.com Chemistry:
http://chemistry.about.com/library/glossary/bldef825.htm
(2013). Retrieved 6 8, 2013, 2 013, from about.com Why Is It Harder to Rinse off Soap with Soft Water? (2013). Chemistry: http://chemistry.about.com/od/howthingsworkfaqs/a http://chemistry.about.com/od/howthingsworkfaqs/a/softwaterrinse.htm /softwaterrinse.htm
