TABLE OF CONTENTS
CONTENTS
PAGES
Abstract
2
Introduction
2
Objectives
4
Theory
5
Apparatus
7
Procedure
7
Results
10
Discussion
12
Conclusion
14
Recommendation
14
References
15
Appendices
16
1
Abstract
This experiment is conducted to determine how the soap is prepared and to show the comparison of the properties between soap and detergent. Firstly, we test for hard water effect of water hardness to the soap and detergent and we also observe and take the result for the precipitation that occurred and also for emulsion when we test by using mineral oil. Therefore, we also compare soap and detergent in the effect of cleanliness, which one is easier to clean tomato sauce and we also test behaviour soap and detergent in acidic condition. From all the result that we get, we can determine the cleaning ability that soap and detergent can achieve. The soap cleaning ability is affected by the water hardness. When the water are polluted by metal ion such as Cl - and also by Fe +, the cleaning ability is decrease because soap now become precipitation when react with metal ion. From the experiment, we can conclude that the detergent is more likely affective as a cleaning method as it worked affectively towards the system that we tested. It does not perform any precipitate or oil emulsified.
Introduction Soap is anionic surfactant used in combination with water for washing and cleaning, which historically comes either in solid bars or in the dorm of viscous liquid. Soap is generic term for the sodium or potassium salts of long-chain organic acids (fatty acids) made from naturally occurring esters in animal fats and vegetable oils. All organic contain the RCO 2H functional group, where R is shorthand notation for methyl, ethyl, propyl, or more complex hydrocarbon chains called alkyl groups. Chemist uses the R shorthand notation because these
groups can be very large and the hydrocarbon chain has little effect on the compound’s chemical reactivity. All esters contain the RCO2H functional group. Hydrocarbon chains that generally contain 12 to 18 carbon atoms are the R groups in soaps. A few examples of soaps is sodium fatty acids such as lauric (vegetable oil), palmitic (palm oil), and stearic (animal fat) acids.
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Saponification is the basic hydrolysis of an ester producing a carboxylic acid salt and an alcohol. A lone pair of electrons on the OH - is attracted to the partially positively charged C atom in the C=O bond in the ester. The C- OR’
bond breaks generating a carboxylic acid
(RCO2H) and an alcohol (R’OH). In the presence of NaOH carboxylic acids are converted to + their sodium salts (RCO2 Na ).
Triglycerides are esters derived from three fatty acids. A triglyceride made from three lauric acid molecules. For examples of triglycerides are fats and vegetable oils. When a triglyceride is saponified, three fatty acid salts (soaps) and glycerols are produced. The R groups in the triglycerides may or may not have the same chain length (same number of carbons). Thus, different types of soaps may be produced from the saponification of a particular triglyceride.
Soaps are useful for cleaning because soap molecules have both a hydrophilic end, which dissolves in water, as well as a hydrophobic end, which is able to dissolve nonpolargrease molecules. Although grease will normally adhere to skin or clothing, the soap molecules can form micelles which surround the grease particles and allow them to be dissolved in water. Applied to a soiled surface, soapy water effectively holds particles in colloidal suspension so it can be rinsed off with clean water. The hydrophobic portion (made up of a long hydrocarbon chain) dissolves dirt and oils, while the ionic end dissolves in water. Therefore, it allows water to remove normally-insoluble matter by emulsification. In other words, while normally oil and water do not mix, the addition of soap allows oils to dissolve in water, allowing them to be rinsed away.
3
Water that contains calcium ions, Ca 2+, and magnesium ions, Mg 2+, is said to be hard water. These ions are leached from ground water flowing over rock formations containing limestone and other minerals. Hard water interferes with the cleaning action of soaps. When soap is added to hard water, insoluble compounds formed which appear as sticky scum. This scum leaves a deposit on clothes, skin, and hair. Ring around the collar will be formed. When it was boiled, hard water leaves a deposit of calcium carbonate, CaCO 3. Detergents nowadays have replaced soap for many cleaning jobs around the home. The development of synthetic detergents by chemists was a great advantage for people with relatively hard tap water in their homes.
Objectives The objectives for this experiment 6 are:
Determine how to prepare a soap
Compare soap’s properties to that of a synthetic detergent
All the differences between soap and synthetic detergent can be determined.
Determine the soap and detergent cleanliness in daily uses
4
Theory
The following is the basic formula for making all soap:
Fatty acid (oil) + Base (lye) = “A Salt” (soap)
The oil or fat is heated gently. Lye and water are combined separately. Lye is where the reacting fat with NaOH will produce a stable soap that will usually become firmer as it cures. Reacting fat with potassium hydroxide will produce a soap that is either soft or liquid. Historically, the alkali used was potassium hydroxide made from the ashes of bracken or from wood ashes.When both ingredients reach the required temperature, they are combined. When the mixture becomes the desired consistency, it is poured into a mould. The bars are then removed from the mould after setting up (approximately 24 to 48 hours). They are restacked and allowed to “cure” or dry until hard. This can take anywhere from 3 to 8 weeks depending on the formula. A synthetic surfactant, a sodium alkyl sulfate called sodium dodecylsulfate, will be prepared by reacting dodecyl alcohol (dodecanol) with sulfuric acid.
The resulting dodecylsulfate is converted to the sodium salt by a reaction with sodium hydroxide.
5
When detergent is added to water, a polar solvent, the molecules form clusters, known as micelles, in which the polar ends of the molecules are on the outside of the cluster and the non-polar ends are in the middle. The cleansing action of soap is determined by its polar and non-polar structures in conjunction with an application of solubility principles. The long hydrocarbon chain is of course non-polar and hydrophobic (repelled by water). The "salt" end of the soap molecule is ionic and hydrophilic (water soluble). The cleaning action of both soaps and detergents results from their ability to emulsify or disperse water-insoluble materials (dirt, oil, grease, etc.) and hold them in suspension in water. This ability comes from the molecular structure of soaps and detergents. When a soap or detergent is added to water that contains oil or other water-insoluble materials, the soap or detergent molecules surround the oil droplets.
The oil or grease is “dissolved” in the alkyl groups of the soap molecules while the ionic end allows the micelle to dissolve in water. As a result, the oil droplets are dispersed throughout the water (this is referred to as emulsification) and can be rinsed away. Soaps are able to clean because they contain natural surfactants (surface acting compounds). Surfactants are necessary because they counter the effects of normally occurring surface tension in wash water. In water droplets that do not contain surfactants, the water molecules are much more attracted to each other than they are to the surrounding air molecules. This causes the droplets to pull in (or tense) on themselves, creating comparatively large, rubbery-surfaced spheres. However, water containing surfactants behaves quite differently. This is because all surfactant molecules have one end which attracts water molecules (a hydrophilic polar end)
and an opposite end that doesn’t (a hydrophobic non -polar end). Therefore, the presence of these “strangely” behaving surfactant molecules alters the usual attraction patterns in water droplets, which would otherwise cause them to pull tightly inward. The lowered surface tension results in relatively small water droplets having surfaces that are less rubbery. These smaller droplets can more easily form very thin sheets of water, as in soap bubbles, therefore more suds are possible. Smaller droplets are also better able to penetrate and lift up dirt particles as well as keep them in suspension. Finally, smaller droplets permit more thorough rinsing. All of these factors contribute to bette r cleaning.
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Materials And Apparatus
Erlenmayer flask
Distilled water
Stir and stirring bar
Ice cube
6M Sodium hydroxide
pH meter
Buchner funnel
Ethanol
Filter paper
Saturated Sodium chloride
Beaker
Vegetable oil
Test tubes
Synthetic detergent
Vacuum filtration
1% of Magnesium chloride
Dropper
1% of Calcium chloride
Scapula
1% of Iron chloride
Analytical balance
1M of HCl
Two pieces of cloths
Tomato sauce
Measuring cylinder
Procedure
Soap Preparation
1. 12.5 mL of vegetable oil was placed in a 250 mL Erlenmeyer flask. 10 mL of ethanol and 12.5 mL of 6M sodium hydroxide solution was added to the flask. To mix the content of the flask the mixture was stirred with stirring bar. The alcohol was carefully smelt by wafting it towards nose. 2. The 250mL flask was heated in a 600mL boiling water bath. 3. To prevent the mixture from foaming the mixture was stirred continuously during the heating process. If the mixture should foam to the point of nearly overflowing, remove the flask from the boiling water bath until the foaming subsides, then continue
7
heating. The mixture was heated for 20-30 minutes or until the alcohol odour is no longer detectable. 4. The paste-like mixture was removed from the water bath and the flask was cooled in an ice bath for 10-15 minutes. 5. The vacuum filtration apparatus was assembled while the flask was cooled. The vacuum flask was secured to a ring stand with a utility clamp to prevent the apparatus from toppling over. 6. A piece of filter paper was weighing to the nearest 0.001g and the mass was recorded. The filter paper was placed inside the Buchner funnel. The paper was moistening with water so that it fits flush in the bottom of the funnel. 7. Once the flask has cooled, 75 mL was added of saturated sodium chloride (NaCl)
solution to the flask to “salt out” the soap. 8. The water at the aspirator was turned on slowly. The mixture from the flask was poured into the Buchner funnel. Once all of the liquid has filtered through the funnel, the soap was washed with 10mL of ice-cold water. The suction filtration was continued until all of the water is removed from the soap. 9. The soap was removed from the funnel and it was pressed between two paper towels to dry it. The filter paper was weighed and the soap was dried and the mass to the nearest 0.001g was recorded and the mass of the soap was determined by difference and the mass was recorded
Comparison of Soap and Detergent Properties-precipitation and Emulsification
1. A stock soap solution is prepared by dissolving 2 g of the soap that we prepared 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 1 is repeated using 2 g of synthetic detergent. When both solutions are cool, the pH of each solution is determined by pH meter. 3. Three test tubes is labelled as test tube 1, 2 and 3. 4 drops of mineral oil is 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. 5 mL of stock synthetic detergent is added to test tube 3.
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4. Each solution is mixed by shaking and let stand for three to five minutes. Note which of the solutions, if any, emulsifies the oil by forming a single layer. 5. The mixtures are poured into the Waste Container. The three test tubes are cleaned and dried. 6. Three more test tubes are labelled as test tube 1, 2 and 3. 2 mL of stock soap solution is placed in each of the three test tubes. 2 mL of 1% CaCl 2, solution is added to test tube 1. 2 mL of 1% MgCl 2 solution is added to test tube 2. 2 mL of 1% FeCl 2 solution is added to test tube 3. Each test tube is shaking to mix the solutions. The observations are recorded. 7. 4 drops of mineral oil is added to each of the test tubes in step 6. Each test tube is shaking to mix the solutions and the solutions are let stand to three to five minutes. If any of solutions emulsified the oil by forming a single layer is noted. 8. Steps 6 and 7 are repeated using 2 mL of stock detergent solution. 9. If any of solutions emulsified the oil by forming a single la yer is noted. 10. The mixtures are poured into the 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 solution is placed in a second test tube. One drop of 1 M HCl is added at a time to both solutions until the pH in each test tube is equal to 3. The number of drops of acid added to each mixture is counted. The precipitates in mixtures are observed. 12. 1 drop of mineral oil is added to each test tube in step 11. Each test tube is shaking to mix the solution. The oil emulsified in the mixtures is observed.
Comparison of the Cleaning Abilities of Soap and Detergent
1. The two beakers are cleaned, dried, and labelled. 20 mL of stock solution is placed in first beaker. 20 mL of stock detergent solution is placed in second beaker. 2. Two cloth test strips that are soaked in tomato sauce are obtained and one strip is placed in each of the beakers. One cloth strip is placed in beaker 1 and one cloth strip in beaker 2. Each solution is stirred repeatedly with a magnetic stir for 5 minutes. 3. The cloth strip is removed from the soap and detergent solution and the excess water is squeezed. Each cloth strip is visually compared to determine their relative cleanliness. The observations are recorded. 9
Results
Soap Preparation
Mass of Filter Paper +
52.0567
Petri Dish, g Mass of Filter paper +
83.4953
Petri Dish + Soap, g Mass of Soap Recovered,
31.4386
g
Comparison of Soap and Detergent Properties
Mass of Soap, g
2.0128
Mass of Detergent, g
2.0771
pH of Soap Solution
11.54
pH of Synthetic Detergent
8.86
Solution
Answer Yes/No SYSTEM
EMULSIFICATION OCCURED
Distilled Water
Yes
Soap
No
Detergent
No
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Hard and Acidic
SYSTEM
PRECIPITATE
Soap
OIL EMULSIFIED
Synthetic
Soap
detergent CaCl2
√
Synthetic detergent
X
√
X
X
√
X
X
X
X
5 drops
2 drops
X
X
(White
(No
precipitate)
precipitate)
(White) MgCl 2
√ (White)
FeCl3
√ (Peach orange)
Acidic
Cleaning comparison of Soap and Detergent
ITEM
Soap
Detergent
OBSERVATIONS
There is no stain on the cloth
The water turns to pale brown colour
There is no stain on the cloth
Water remains unchanged in colour
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Discussion In our daily lives, we frequently use cleansing products such as soap and detergent. We use these products to clean our skin and hands wash our clothes without really want to know how they work or is there any difference between them. Maybe soap and detergent are perform same action which is cleansing but there are difference between them. Here, we are conducted this experiment to achieved or study how the soap is prepared and most importantly the comparison of properties of soap and detergent. We know that soap and detergent are used as cleaning agent in our everyday lives. These products are sodium salts of organic acids. They are special organic acids that have long chain hydrocarbons with hydroxyl groups. These types of acids are also called fatt y acids. Before we compare the properties of soap and detergent, we look first how to prepare the soap. A more basic explanation is the oil or fats combine with Sodium Hydroxide or
“Lye” in a process called saponification to produce soap. The vegetable oil had b een mixed with some amount of ethanol which an acid and 6M of NaOH solution as a base. The mixture will undergoes heating process until the alcohol odour is no longer detectable. Then, the mixture had been cooled and the vacuum filtration apparatus was prepared, the saturated HCl was added to the flask. Next, the mixture was poured into the Buchner funnel until the liquid is removed from the soap. The soap was taken out then dried it. The dried soap which had been prepared can be weighed in order to know the mass. In this experiment, we determined the differences properties between soap and detergent in term of precipitation, emulsification, behaviour in acidic condition, and also cleaning ability. For part one, we compare the soap and detergent with distilled water to emulsification properties. This shows that only detergent produce clear solution compared to soap and distilled water. Here, we know that detergent more effectiveness that soap in emulsification condition. This result can be explain because the molecule of soap contain hydrophilic ion which dissolved in water while another one is hydrophobic ion which dissolved in oil or grease. Distilled water is polar molecule thus it cannot dissolve in oil or grease. For the next part, we want to determine the properties of soap and detergent in hard water and acid condition. As we can see in the result, the soap form a precipitate when react with water that contain mineral salts while the detergent not form the precipitate. Moreover,
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the emulsion occurred when the detergent reacts with mineral salts except for Fe + and no emulsion occurred for soap. This show that the soap reaction gives effect with water hardness but the detergent reaction is not affected. Although soap is good cleaning agent, its effectiveness is decrease when used in hard water. Hardness water caused by the presence of mineral salts such as calcium (Ca), magnesium (Mg), and iron (Fe) and also manganese (Mn). The mineral salts reacts with soap to foam an insoluble precipitate known as soap film or scum. Water hardness give a problem for soap to react and the effectiveness of cleanliness are low compare with the detergent. The most important difference between a soap and detergent is their behaviour in water. The soap will form a scum in hard water, which are not easy to clean. So, to avoid the scum problem we need to soften the hard water by removing the hard water ions. This way we had known as ion exchange technique. On the other hand, detergent react less to minerals in water hence does not leave this residue or scum. Then, we compare the acidic behaviour of the soap and detergent. We can say that soap is more alkaline than detergent. Soap has a high pH value than detergent. It is becausewhen we conducted the experiment for this part, we only used 6 drops of HCl to add to the detergent solution will make the solution become to pH nearest to 3. However, the soap needs about 10 drops to turn the pH of solution to pH nearest to 3. Last part, we want to determine the cleaning action of the stock soap solution and stock detergent solution with the cloths that were soaked into tomato sauce. The stock of two solutions is placed into two difference beakers and then the two strips of cloth that soaked with tomato sauce are put into each of the beaker. After three or five minutes, we can see that the strips that soak in stock detergent solution are making the strip become very clean and the follow by the stock soap solution. The strip that soak in stock soap solution are also clean but not clean as detergent and we also can see that the red colour of tomato sauce are still occur on the strip and water. Therefore, we can conclude that detergent is more effectively cleansing that soap. This can be explaining by the soap solution was salt weak acid. It works towards dirt as a wetting agent that reduced the surface tension of water, allowing the water molecules to encounter the dirty object. Water is a polar species, and dirt frequently is a non polar species. These to substance will dissolve each other. Synthetics detergent was made to encounter the weakness of soap that is can diss olve in polar and non-polar solution.
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CONCLUSION Our experiment is successfully. From this experiment and all results that we get, we can conclude that detergent is effective compare to the soap. We can compare the properties of soap and detergent and we also can compare the advantages and disadvantages of using soap and detergent in our daily lives by doing this experiment. Soap may perform precipitate or oil emulsified towards certain condition. Then, we also know that the water hardness give a problem for soap to react and the level of cleanliness are low compare to detergent. Soap is more alkaline compare to the detergent. So, it may not be as effective as synthetic detergent. Moreover, in cleansing action, soaps have weak action in cleaning the cloth compare to detergent. Therefore, from what we observes and results that we get from this experiment, we can conclude that detergent is more effective than the soap. However, during us conducting this experiment, a few errors or an improper behaviour maybe occurred. So, to get more accurate results, we should observe the changing of solution or results carefully. Besides, we can obtain the good result by repeat this experiment twice and clean up the apparatus that have been used nicely. In addition, this experiment needs to use a lot of test tubes to test and observe on different properties of soap and detergent solution. Thus, we should used different test tubes if the lab has enough test tubes because this can avoid the inaccurate results. This is because when we used the same test tube doing this experiment, the residue that have in test tube maybe can affect the results and observations of experiment.
RECOMMENDATIONS
There are a few recommendations that indicate how experimental techniques or apparatus could be improved in light of the conclusion arrived at and the consistency of the experimental results in relation to the theory. In this experiment, there was a step where both of the soap solution and detergent solution need to be determined the value of pH. We have improved the way to read the value of pH. We use the pH meter than using the indicators 14
because pH meter is more accurately, suitable and easy to use. When we want to know the equivalence point in this experiment, so if we use the old way by using the indicator there is difficult to observer to get the accurate value by observe the change of the colour. Besides that, in order to get the accurate value of pH, both solution need to be cool before the pH value is determined. It is because the value of pH of the solution when warm is not constant and the values when warm and cool were different. Next, we can improve the way we stirred the solution. We use magnetic stirrer than the glass rod because it is more efficient. The solution will take the short time to mix and become homogeneous. Besides that, when we want to stir the soap and detergent solution using the analytic balance maybe we can split out some of the solutions. So, we must to careful with the speed of the magnetic stirrer for mix the solutions. Other than that, there was also as step that the observer must take the number of drops of the chemical reagent. So that, the observer must count the number of drop the used of the chemical reagent as the solution had finish the reactant. The observer also must alert with the pH when drop the acids. To avoid the big deviate pH value, drop the acids slowly.
REFERENCES
UiTMChemisty Engineering, Lab Manual Experiment 6, Soap And Detergent
http://www.wikipedia.com/soap.htm
http://chemistry.caltech.edu/courses/ch15/soap
http://chemistry.caltech.edu/courses/ch15/detergent
http://www.cleaning101.com/sdalatest/html/soapchemistry1.htm
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APPENDICES
16
