Page " 16
Contents
Abstract / Summary 2
Introduction 3
Aim / Objective 4
Theory 5
Procedure 8
Apparatus and materials 11
Result 12
Discussions 15
Conclusions 16
Recommendations 16
References 17
Appendices 17
Abstract / Summary
Soap is a 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. Saponification is the basic hydrolysis of an ester producing a carboxylic acid salt and an alcohol.
The purpose for this experiment is used to prepare the soap and to compare its properties to that of a synthetics detergent. Then, to know the existence in the form of precipitation, emulsification and cleaning abilities between soap and synthetic detergent. Prepare soap by saponification method. The soap had been made and used various test to determine its properties.
Soap prepared then compared with synthetics detergent by using oil emulsification test, pH test, hard water test, acidic test and also cleansing test. The hard water test use CaCl2, MgCl2 and FeCl3.
Based on the experiment that had been conducted, it can be concluded that the soap has the properties of emulsifying oil whereas the synthetics detergent has not as soap has precipitates while detergent has not forms precipitates at all.
For comparison for cleansing abilities is the most clean is diluted detergent while soap is just clean and less clean is pure detergent.
Overall, it we can conclude that diluted synthetics detergent is cleaner than dilute soap. The experiment is completed and successfully conducted.
Introduction
Soap is a 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 acids contain the RCO2H functional group, where R is a shorthand notation for methyl, CH3-, ethyl CH3CH2-, Propyl, CH3CH2CH2-, or more complex hydrocarbon chains called alkyl groups. Chemists use 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 RC02R functional group.
The R groups in soaps are hydrocarbon chains that generally contain 12 to18 carbon atoms. Sodium fatty acids such as lauric (vegetable oil), palmitic (palm oil), and stearic (animal fat) acids are just a few examples of soaps.
CH3(CH2)10COONa sodium laurate
CH3(CH2)16COONa sodium stearate
The hydrocarbon chain in soaps may contain saturated (no double bond) or unsaturated chains (contains double bonds). Sodium salts are usually solid therefore; most bars of soap are of sodium salts. Potassium salts are the basis of liquid soaps, shaving creams, and greases. Fats and vegetable oils are triglycerides. Triglycerides in an ester derived from three fatty acids. A triglyceride made from three lauric acid molecules is shown in Figure 6-1.
Saponification is the basic hydrolysis of an ester producing a carboxylic acid salt and an alcohol (Eq.3-1) .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 (Eq.6-1). The C-OR' bond breaks generating a carboxylic acid (RC02H) and an alcohol (R'OH). In the presence of NaOH, carboxylic are converted to their sodium salts (RCO2-Na+).
When a triglyceride is saponified, three fatty acid salts (soaps) and glycerol are produced as shown in Equation 6-2. The R groups in the triglyceride 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.
Figure 6-1: A Triglyceride molecule made from lauric acid and glycerol
(Equation 6-1)
(Equation 6-2)
Aim / Objective
Prepare soap and compare its properties to that of a synthetics detergent.
Theory
Soap is the salt of a weak acid. Most organic acids arc weak acids. Consequently, hydrolysis occurs to some extent when soap dissolves in water. Soap solutions tend to be slightly alkaline (basic) due to partial hydrolysis of the acid (Eq. 3).
(Equation 6-3)
The cleansing action of soaps results from two effects. Soaps are wetting agents that reduce the surface tension of water, allowing the water molecules to encounter the dirty object. They are also emulsifying agents. "Dirt" frequently consists of a grease or oil along with other organic species. In general, organic compounds are nonpolar. Water is a polar species. These two substances will not dissolve in each other because of their dissimilar characteristics (the "Like Dissolves Like" rule). Soaps cross the boundary between polar and nonpolar because they contain a polar hydrophobic (water- hating) end and a polar hydrophilic (water loving) end as shown in Figure 6-2.
Figure 6-2: Molecular structure, a) a line drawing, b) of sodium stearate. In a line drawing, all carbon and hydrogen atoms are omitted at the intersection of each line as a shorthand method of drawing molecule. It is understood that the C and H atoms are part of the molecule.
Because soaps have both polar and nonpolar region in the molecule, they are soluble in both polar and nonpolar species. The hydrophobic (nonpolar) portion of soap is soluble in nonpolar compound like grease and oils. The hydrophilic (polar) end dissolves in water. Soap molecules surround the grease and oils and break them up into microscopic droplets can remain suspended in the water. These suspended microscopic droplets are called micelles (Figure 6-3). Micelles contain very small amounts of oil or grease in their centre. Thus the oil or grease has been dissolved in water forming an emulsion, one form of a suspension in water.
Figure 6-3: Formation of micelle
Water supplies in certain areas are acidic as a result of acid rain or pollution, or "hard" due to the dissolved mineral content. Both acidic and "hard" water reduce the cleansing action of soap. Soap is the salt of a weak acid. In the presence of a stronger acid, the sodium salt is converted to an insoluble organic acid (Eq. 3-4).
(Equation 6-4)
"Hard water" contains dissolved Ca2+ , Mg2+ , and Fe 3+, ions from the minerals that the water passes over. Normally, soaps made from sodium and potassium fatty acid salts are soluble in water. However, in the presence of these metal ions, the Na+ and K+ soluble salts convert to insoluble Ca2+ , Mg2+ , and Fe 3+ salts (E q. 3-5).
(Equation 6-5)
In either acidic or "hard" water, the soluble soaps form insoluble salts that becomes a scummy ring on bathtubs and black areas on shirt collars .The cleansing ability of soap is reduced because soap molecules are removed from solution. There are several techniques used to circumvent the problems generated by hard water. Water can be "softened" via removing hard water ions from solution using ion exchange techniques or by adding water-softening agents, such as sodium phosphate (Na3PO4) or sodium carbonate (Na2CO3). Water-softening agents react with the Ca2+ , Mg2+ , and Fe 3+, removing them from water (Eq. 6-6 and 6-7) and preventing the reaction of these ions with soap (Eq. 6-4 and 6-5).
(Equation 6-6)
(Equation 6-7)
Thus "Syndets" was design to overcome the soap problem with "hard water". Syndets differ from soaps in that the nonpolar fatty acids groups are replaced with alkyl or aryl sulfonic acids (ROS03H). The alkyl or aryl sulfonic acids have long chains of carbon atoms giving the hydrophobic (nonpolar) end. The salt of the sulfonic acid (sulfonate) group forms the hydrophilic end of the molecule. The difference in polar groups is one of the key distinctions between a soap and a synthetic detergent. Syndets form micelles and cleanse in the same manner as soaps. Two examples of synthetic detergents are shown in Figure 6-4.
Figure 6-4: Examples of synthetics detergents
Because sulfonic acid is a stronger acid than carboxylic acids, Syndets do not precipitate in acidic solutions. Furthermore, alkyl and aryl sulfonates do not form insoluble salts in the presence of the typical hard water ions. Thus, synthetic detergents remain soluble in both acidic and "hard" water.
Procedure
2.4.1 Soap preparation
12.5 mL of vegetable oil is placed in a 250-mL Erlenmeyer flask.10 mL of ethanol and 12.5 mL of 6 M sodium hydroxide solution added to the flask. Stirred the mixture with the stirring rod to mix the contents of the flask.
250-mL flask in a boiling-water bath heated inside of a 600-mL beaker.
The mixture stirred continuously during the heating process to prevent the mixture from foaming. 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 heating. The mixture heated for 20-30 minute or until the alcohol odour is no longer detectable.
Removed the paste-like mixture from the boiling-water bath and cooled the flask in an ice bath for 10-15 minutes.
While the flask is cooling assemble the vacuum filtration apparatus shown in Figure 3-5. Secure the vacuum flask to a ring stand with a utility clamp to pre-vent the apparatus from toppling over.
Figure 6-5: Vacuum Filtration apparatus
Weighed a piece of filter paper to the nearest 0.001 g and recorded the mass. Placed the filter paper inside the Buchner funnel. Moisten the paper with water so that it fits flush in the bottom of the funnel.
Once the flask has cooled, added 150 mL of saturated sodium chloride (NaCl) solution to the flask to "salt out" the soap.
Slowly turned on the water at the aspirator. Poured the mixture from the flask into the Buchner funnel. Once all of the liquid had filtered through the funnel, washed the soap with 10 mL of ice-cold water. Continued the suction filtration until a11 of the water is removed from the soap.
Removed the soap from the funnel and pressed it between two paper towels to dry it. Weighed the filter paper and dried soap, and record the mass to the nearest 0.001 and determined the mass of the soap by difference and recorded the mass.
2.4.2 Comparison of soap and detergent properties- precipitation and emulsification
Preparing a stock soap solution by dissolving 2g of your prepared soap in 100 mL of boiling, distilled water. Stirred the mixture until the soap has dissolved and allow the solution to cool.
Step 1 was repeated using 2 g of synthetic detergent (e.g., Dynamo). When both solutions are cooled, determined the pH of each solution using pH paper.
Three test tubes were labelled as test tube 1, 2, and 3. Added 4 drops of mineral oil to each test tube. Added 5 mL of distilled water to test tube 1. Added 5 mL of stock soap solution to test tube 2. Added 5 mL of stock synthetic detergent to test tube 3.
Each solution mixed by shaking and let stand for three to five minutes. Noted which of the solutions, if any, emulsifies the oil by forming a single layer.
Poured the mixtures into the Waste Container. Cleaned and dried the three test tubes.
Three test tubes were labelled as test tube 1, 2, and 3. Placed 2 mL of stock soap solution in each of the three test tubes. Added 2 mL of 1% CaCl2 solution to test tube 1. Added 2 mL of 1% MgCl2 solution to test tube 2. Added 2 mL of l% FeCl2 solution to test tube 3. Shake each test tube to mix the solutions. Observation was recorded.
Added 4 drops of mineral oil to each of the test tubes in Step 6. Shake each test tube to mix the solutions and let the solutions stand for three five minutes.
Note which of the solutions, if any, emulsifies the oil by forming a single layer.
Steps 6-7 repeated using 2 mL of stock detergent solution. Which solutions form a precipitate?
Note which of the solutions, if any, emulsifies the oil by forming a single layer.
Poured the mixtures into the Waste Container. Cleaned and dried the test tube.
Placed 5 ml of stock soap solution in cine clean test tube and 5 mL of stock detergent solution in a second test tube. Added 1 M HC1 one drop at a time to both solutions until the pH in each test tube is equal to 3. (Use pH paper to measure).Count the number of drops of acid added to each mixture. Does a precipitate form in either mixture?
Added 1 drops of vegetable oil to each test tube in Step 11. Shake each test tube to mix the solution. Is the oil emulsified in either mixture?
2.4.3 Comparison of the cleaning abilities of a soap and detergent.
Cleaned, dried, and labelled three beakers. Placed 20 mL of stock soap solution (from Step 1 in section 2.4.2) in the 1st beaker. Placed 20 mL of stock detergent solution (from Step 2 in section 2.4.2) in the 2nd beaker. Placed 20 mL of a commercial liquid Dynamo.7
Obtained three cloth test strips that have been soaked in tomato sauce and place one strip in each of the beakers. Place one cloth strip in beaker 1 (from above), one cloth strip in beaker 2, and one cloth strip in beaker 3. Repeatedly stir each solution with a stirring rod for 5 minutes.
Removed the cloth strips from the soap and detergent solution and squeeze out the excess water. Visually compared each cloth strip to determine their relative cleanliness. Observations was recorded.
Apparatus and materials
List of apparatus:
600mL beaker
250mL Erlenmeyer flask
Stirring rod
Stopwatch
Retort stand
Measuring cylinder
Filter paper
Vacuum filtration apparatus
High precision analytical weighing balance
Spatula
pH paper
Test tubes labelled (1,2 and 3)
Dropper
Cloth test strips
Heater
List of materials:
12.5mL of vegetable oil
10mL of ethanol
12.5mL of 6M sodium hydroxide
An ice
150mL of saturated sodium chloride
Distilled water
Synthetic detergent
Commercial liquid Dynamo
1% calcium chloride solution
1% magnesium chloride solution
1% iron (II) chloride solution
Vegetable oil
1M hydrochloric acid
Tomato sauce
Mineral oil
Result
2.4.1 Soap preparation
Mass of filter paper (g)
0.5418
Mass of filter paper + soap (g)
3.6438
Mass of soap recovered (g)
3.1020
2.4.2 Comparison of soap and detergent properties- precipitation and emulsification
Brand name of synthetics detergent
Dynamo
pH of soap solution
10
pH of synthetics detergent solution
8
System
Test tubes
Emulsification Occur
Distilled water
1
Broken emulsion
Soap
2
Stable emulsion
Detergent
3
Broken emulsion
System
Precipitate
Oil emulsified
Soap
Detergent
Soap
Detergent
CaCl2
Has precipitate
No precipitate
MgCl2
No precipitate
No precipitate
FeCl3
Has precipitate
No precipitate
CaCl2 + mineral oil
Broken emulsion
Stable emulsion
MgCl2 + mineral oil
Broken emulsion
Stable emulsion
FeCl3 + mineral oil
Broken emulsion
Stable emulsion
Sample
Soap
Detergent
No of drops of HCl
8
2
First observation
Has precipitate
No precipitate
Second observation
Broken emulsion
Stable emulsion
2.4.3 Comparison of the cleaning abilities of a soap and detergent.
Sample
Cloth strips observation
Soap solution
Clean
Detergent (dilute)
More clean
Detergent (pure)
Less clean
Discussions
Soap is a 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. Saponification is the basic hydrolysis of an ester producing a carboxylic acid salt and an alcohol. Soap is the salt of a weak acid. Most organic acids arc weak acids. Consequently, hydrolysis occurs to some extent when soap dissolves in water. Soap solutions tend to be slightly alkaline (basic) due to partial hydrolysis of the acid.
For part 2.4.1 Soap preparation at the end of this experiment, total soap produced is 3.1020g. Using vacuum filtration apparatus to gain total mass of soap recovered.
For part 2.4.2 Comparison of soap and detergent properties- precipitation and emulsification we are using pH test, it can be said that soap is more alkaline than detergent which pH for soap is 10 while detergent is 8. Next, we are using emulsification test which 5 ml of detergent, soap solution and distilled water. For distilled water and detergent has broken emulsion while soap solution got stable emulsion.
For hard water test, soap solution and detergent had been tested with calcium chloride, magnesium chloride and iron (III) chloride. First observation for soap solution is there are precipitation in soap solution when CaCl2 and FeCl3 were added while no precipitate when MgCl2 was added. Meanwhile for detergent, there is no precipitate formed after CaCl2, MgCl2 and FeCl3 were added. Second observation is for when a few drops of vegetable oil is added into the same samples. The results shows that soap solution have broken emulsion for all while detergent have stable emulsion for all.
As for acidic test, to let the pH drop to 3 a few drops of HCl must be added into the solution. The soap solution required 8 drops of HCl and has precipitate formed while detergent required 2 drops of HCl and there is no precipitate formed. After a drop of vegetable oil were added into both samples, broken emulsion occur in soap solution while stable emulsion in detergent.
For part 2.4.3 Comparison of cleaning abilities of a soap and detergent is about as a final test, to determine the effectiveness of soap and detergent in cleaning stain on the cloth strips that have been soaked in tomato sauce. The relative cleanliness can be conclude as
Pure detergent < Soap solution < Diluted detergent
Conclusions
Conclusion
In conclusion, the soap is successfully prepared and the comparison properties of soap and detergent which are precipitation, emulsification and cleaning abilities are made has been observed and recorded.
From this experiment and all results that we get, we can conclude that detergent is effective compare to the soap. It can be concluded that detergent is more effective cleaning agent rather than soap. Soap may perform precipitate or oil emulsified towards certain condition. Then, we also know that the water hardness should 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. Therefore, it may not be as effective as synthetic detergent as detergent can makes cloth cleaner than clean it using soap solution and also soap solution leaves scum at the cloth.
However, there a few errors that might be occur during conducting experiment. Firstly, we might be misinterpret when observe the changing of solution or not observe accurately. Next, this experiment are not repeated twice and probably apparatus used are not totally cleaned. By using same test tubes also might be affected the results and observations of experiment. Besides we might read the pH for soap solution and detergent in the wrong way since we just using pH paper not pH electrode.
Recommendations
To get the accurate value of result in the experiment, there are a few recommendations and precaution that need to be considered through the experiment. These recommendations and precautions could be improve the results and observation if this experiment are conducting again.
Firstly, we must be alert when there are any reagent are added into the samples as it might has fast reactions occur and also observe the samples clearly. Furthermore, clean and dry all the apparatus before experiment get started and repeat the experiment twice to get more accurate results. Next, try to using different test tubes to avoid it from affected the results and observations. By using pH electrodes, our pH reading maybe more tally, accurate and easy to use rather than if we are using pH paper as there is difficulty to observe the colour.
In conclusions, we should wear gloves and goggles while conducting the whole experiment as a safety precautions step.
References
CHE485-CHRISTINA VARGIS-SHAH ALAM-Lab manual-Lab manual (Exp6). (n.d.). Retrieved March 28, 2017, from http://i-learn.uitm.edu.my/main/default-frame.php
https://www.scribd.com/document/146911988/Lab-Report-6-Soap-And-Detergent-Uitm
http://download.docslide.net/documents/lab-6-uitm-soap-preparation-comparison-soap-and-detergent-properties.html
http://documentslide.com/documents/exp-6-soap-and-detergent.html
Appendices
