Chem Lab (Soaps)

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UNIVERSITI TEKNOLOGI MARAFAKULTI KEJURUTERAAN KIMIA

ENGINEERING CHEMISTRY LABORATORY

(CHE485)

No. Title Allocated Marks (%) Marks

1 Abstract/Summary 5

2 Introduction 5

3 Aims 5

4 Theory 5

5 Apparatus 5

6 Methodology/Procedure 10

7 Results 10

8 Calculations 10

9 Discussion 20

10 Conclusion 5

11 Recommendations 5

12 Reference / Appendix 5

13 Supervisors grading 10

TOTAL MARKS 100

Remarks:

Checked by : Rechecked by:

--------------------------- ---------------------------

Date: Date:

NAME : IKHWAN BIN HASBULLAH

STUDENT NO. : 2010245466

GROUP : EH 220 2A

EXPERIMENT : SOAP AND DETERGENT

DATE PERFORMED : 21ST

& 28TH

JANUARY 2011

SEMESTER : 2

PROGRAMME / CODE : CHEMICAL ENGINEERING / EH 220

SUBMIT TO : PN SYAFIZA ABD HASHIB


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Table of content

CONTENT PAGE

Abstract / summary 3

Introduction 4

Objectives 6

Theory 6

Apparatus 11

Procedures 12

Result 14

Sample of calculations -

Discussions 16

Conclusions 18

Recommendations 19

References 19

Appendices -


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Abstract / Summary

In this experiment, we were assigned to make our own soap vegetable oil and ethanol.

For the preparation of soap, we had recovered 23.027 g of soap from 20 mL of vegetable oil and

20 mL ethanol. Soaps are the salts of a weak acid. Soaps have both polar and nonpolar region in

the molecule, they are soluble in both polar and nonpolar species. Syndets was design to

overcome the soap problems with hard water. Syndets differ from soap in that the nonpolar fatty

acid group is replacing with alkyl or aryl sulfonic acids (ROSO3H). The objectives of the

experiment were to prepare soap and to compare it properties with synthetic detergent. In order

to achieve the objectives, firstly, the solution was added with mineral oil to detect if any

emulsification occurred in the solution. Next, the solution was added with 1% CaCl2, 1% MgCl2

and 1% FeCl3 and the precipitation and oil emulsification was determined by this method. Lastly,

the soap and detergent and also commercial liquid was compared in cleansing ability using test

cloth strips which soaked with tomato sauce. It was found that the commercial liquid was really

better in cleansing process. Between the soap and detergent, it was found that detergent was

more effective than soaps. It also shows that synthetic detergent have more advantages than soap

in cleaning industries.


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Introduction

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 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 used the R shorthand notation because these groups can be very large and the

hydrocarbon chain has little effect on the compounds chemical reactivity. All esters contain the

RCO2R functional group.

The R groups in soaps are hydrocarbon chains that generally contain 12 to 18 carbon

atoms. Sodium fatty acids such as lauric (vegetable oil), palmitic (palm oil) and stearic (animals

fat) acids are just a few examples of soaps.

CH3 (CH2)10COONa sodium laurate CH3 (CH2)16COONa sodium stearate

The hydrocarbon chain in chain in soaps may contain saturated (no double bond) or

unsaturated (contains double bonds). Sodium salts are usually solid therefore; most bars of soap

are sodium salts. Potassium salts are the basis of liquids soaps, shaving creams and greases. Fats

and vegetable are triglyceride. Triglyceride in an ester derived from three fatty acids. A

triglyceride made from the from three lauric acid molecules is shown in Figure 7-1.

Saponification is the basic hydrolysis of an ester producing a carboxylic acid salt and an

alcohol (Eq. 7-1). 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. 3-1). The C-OR bond breaks generating a

carboxylic acid (RCO2H) and an alcohol (ROH). In the presence of NaOH, carboxylic are

converted to their sodium salts (RCO2-Na+).


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When a triglyceride is saponified three fatty acid salts (soaps) and glycerol is produced as

shown in Equation 7-1. 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 triglyceride.


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Objectives

Prepare a soap and compare its properties to that of a synthetic detergent.

Theory

Soaps are the salts of a weak acid. Most organic acids are weak acids. Consequently, hydrolysis

occurs to some extent when soap dissolved in water. Soaps solutions tend to be slightly alkaline

(basic) due to partial hydrolysis of the acid (Eq. 3).

O O

R C + H2O R C + NaOH (Equation 7-3)

O-Na

+OH

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 agent. 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

Dissolved Like). 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 3-2.


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Figure 7-2: Molecule structure, a) a line drawing, b) of sodium stearate.

Soaps have both polar and nonpolar regions, hence they are soluble in both polar and

nonpolar species. The hydrophobic (nonpolar) portion of soaps is soluble in non polar compound

like grease and oils. The hydrophilic (polar) end dissolves in water. Soaps molecules surround

the greases and oils and break them up into microscopic droplets can remain suspended in water.

These suspended microscopic droplet are called micelles (Figure 3-3). Micelles contain very

small amounts of oil or grease in their center. Thus the oil or grease has been dissolved in water

forming an emulsion, one form of a suspension in water.


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Figure 7-3: Formation of Micelle

Water supplies in certain areas are acidic as a result of acid in rain or pollution, or hard

due to the dissolved mineral content. Both acidic and 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).

O O

CH3(CH2)16CO-Na

++ H

+CH3(CH2)16CO H + Na

+

Soluble soap insoluble acid (Equation 7-4)

Hard water contains dissolved Ca2+

, Mg2+

and Fe3+

ions from the mineral that the water

passes over. Normally, soaps made from sodium and potassium acid salts convert to insoluble

Ca2+

, Mg2+

and Fe3+

salts (Eq.3-5).


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O O

2CH3(CH2)16CO-Na+ + Ca2+ (CH3(CH2)16CO)2Ca

2+ + 2Na+

Soluble fatty acid salts (soap) insoluble fatty acid salt (Equation 7-5)

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 soaps is

reduced because soap molecules are removed from solution. There are several techniques used

circumvent the problems generated by hard water. Water can be softened via removing hard

water ions from solution using ion exchanger techniques or by adding water softening agent,

such as sodium phosphate (Na3PO4) or sodium carbonate (Na2CO3). Water softening agents react

with the Ca2+, Mg2+ and Fe3+ removing them from water (Eq 7-4 and 7-5).

3 Ca2+

(aq) + 2PO43-

(aq) Ca3(PO4)2(s) (Equation 7-6)

Mg2+(aq) + CO32-

(aq) MgCO3(s) (Equation 7-7)

Thus Syndets was design to overcome the soap problems with hard water. Syndets

differ from soap in that the nonpolar fatty acid group is replacing with alkyl or aryl sulfonic acids

(ROSO3H). The alkyl or aryl sulfonic acids have long chains of carbon atoms are giving the

hydrophobic (nonpolar) end. The salt of the sulfonic acids (sulfonate) groups form the

hydrophilic end of the molecule. The difference in polar groups is one of the key distinctions

between soap and a synthetic detergent. Syndets form micelles and cleanse in the same manner

as soaps. Two example of synthetic detergent are shown in Figure 7-4.


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Figure 7-4: Example of synthetics detergents

Because sulfonic acid is a stronger acid than carboxylic acids, syndets do not precipitate

in acidic solutions. Furthermore, alkyl and aryl sulfonate 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.


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Apparatus & Chemicals

250mL Beaker 50mL beaker 10mL Cylinder 10mL volumetric pipette Test tube Stirrer rod Typical Burette pH meter Soaps Detergents


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Procedures

Comparison of soap and detergent properties- precipitation and emulsification.

1. Prepared the stock solution by dissolving 2g of prepared soap in 100mL of boilingdistilled water. The mixture was stir until the soap was dissolved and allowed the solution

to cooled.

2. Step 1 was repeated using 2g of synthetic detergent (dynamo). The pH was determinedwhen the solution was cooled.

3. 3 test tubes were labeled and 4 drop of mineral oil added into each test tube. 5mL ofdistilled water, stock soap solution and stock synthetic detergent added into test tube 1, 2

and 3.

4. Each solution mixes with shaking and let it stand about 3 to 5 minutes.5. The solution was cleaning and dry the tubes.6. 2mL stock solution placed into each tubes and 2mL of 1% CaCl2, 1%MgCl2 and

1%FeCl2 added into test tube 1, 2 and 3. The solution shake to mix and the observation

was recorded.

7. 4 drops of mineral oil added to each test tube in step 6 and test tubes was shake to mixes.The solution was leaves for 3 to 5 minutes to record the change.

8. Steps 6-7 was repeat using 2mL of stock detergent solution.9. The solution was pour into waste container and clean and dry the test tubes.10.5mL of stock soap solution, stock detergent solution placed into clean test tubes. Added 1

M of HCL one drop at time to both solutions until the pH in each test tube is equal to 3.

11.1 drops of mineral oil was added into each test tube in step 11. Each test tube was shaketo mixes.


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Comparison of the cleaning abilities of a soap and detergent.

1. 20mL of stock solution (from step1 in experiment 1), stock detergent solution (from step2 in experiment 1) and liquid Dynamo placed in beaker then label 1, 2 and 3.

2. 3 cloths test strips obtained been soaked in tomato sauce and place one strip in each ofthe beaker. Cloth strip placed in each beaker. Each solution was stir repeatedly with

stirring rod for 5 minutes.

3. Removed the cloth strips from the soap and detergent solution and squeezed out theexcess water. Visually compared each cloth strip to determine their relative cleanliness.

Observations were recorded.


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Results

Comparison of Soap and Detergent Properties

Brand name of synthetic detergent Dynamo

pH of soap solution 11.43

pH of synthetics detergent solution 8.39

System Emulsification Occurred

Distilled Water Yes

Soap No

Detergent Yes

System

Precipitate Oil Emulsified

Soap Syndet Soap Syndet

CaCl2 Yes No No No

MgCl2 Yes No No Yes

FeCl3 Yes No Yes Yes

Acidic Yes No No No

Drops of HCl in soap = 2 drops

Drops of HCl in syndet = 1 drops


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Cleansing Ability

Stock soap solution Third

Stock detergent solution Second

Commercial Liquid First


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Discussions

This experiment was conducted to compare the soaps properties to that of a synthetic

detergent. In this experiment we used the Dynamo with pH 8.39 when diluted in boiled distilled

water and used as synthetic detergent. The pH of soap solution was measured to be 11.43.

Soaps are wetting agents that reduce the surface tension of water and allow water to

encounter the dirty object. Soaps are also the emulsifying agents. That is proven when the

mineral oil was added to the distilled water, soaps solution and synthetic detergent, the soaps

solution and the detergent was emulsified the oil by forming a layer in the test tube. That were

shown that emulsification was occurred in the soaps and detergent. In general, there are two

species of substances which are organic compounds and water. Organic compounds are nonpolar

but water is a polar species. Soaps cross the boundary between polar and nonpolar because they

contain a polar hydrophobic (water-hating) tail and a polar hydrophilic (water loving) head.

Hence, they are soluble in both polar and nonpolar species.

The suspended microscopic droplets or micelles that formed from the soaps operation,

and remain in water will cause the water to be polluted or hard. That is what the synthetic

detergent will discover, which is to overcome the hard water problem caused by the soaps. For

second experiment, the 1% CaCl2, 1% MgCl2 and 1% FeCl3 were added to the solution in order

to detect if there were any precipitation and oil emulsification will occurred in the both solutions.

This experiment was shown that precipitation was occurred in soaps solution when 1% CaCl2,

1% MgCl2 and 1% FeCl3 were added.


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However, differ with detergent, there were no precipitation occurred when the three

solution were added. That is why the detergent was differed from the soaps. It is because the

nonpolar fatty acids groups in the soaps was replaced with alkyl or aryl sulfonic acids and give

the difference in polar groups. Other than that, both soaps and detergents solution was added

with acidic, and the results was remained the same which precipitation occurred in soaps but not

in detergent. The sulfonic acids was stronger than carboxylic acids and contain in detergent

caused the detergent not precipitate in acidic solutions. Besides, it do not form insoluble salts in

the presence of typical hard water ions and remain soluble in both acidic and hard water.

For oil emulsified experiment, the soap did not emulsify in 1% CaCl2 and 1% MgCl2 and

also in acidic solution. However, the synthetic detergent (syndet) was emulsified in 1% MgCl2

and 1% FeCl3. For other experiment, HCl was added in both solutions until the pH was 3 and the

drops of HCl added to the solution were calculated. For soaps solution it need about 2 drops of

HCl in order to reach the needed pH but only 1 drops needed in the detergent solutions.

For cleansing ability experiment, three solutions which were stock soap solution, stock

detergent solution and commercial liquid. The test cloth strips which soaked with tomato sauce

were used to determine the cleansing ability. It was found that the commercial liquid was greater

in the cleansing ability followed by stock detergent solution and lastly the stock soap solution.

By using commercial liquid, the cleansing process occurred effectively which the test cloth strips

was very clean.


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Conclusions

There were three methods that were used to compare between the soap and detergent

properties. Dynamo with pH 8.39 was used as the synthetic detergent with the soap with the pH

11.43. Soaps are wetting agents that reduce the surface tension of water and allow water to

encounter the dirty object. Soaps are also the emulsifying agents. That is why emulsification was

occurred in soap and detergent when mineral oil was added in both solutions. Detergent was

differ from the soap because the nonpolar fatty acids group was replaced with alkyl or aryl

sulfonic acids that caused no precipitation in acidic solution when added with 1% CaCl2, 1%

MgCl2 and 1% FeCl3. It is because the sulfonic acid was stronger than carboxylic acids. For

cleansing ability, the commercial liquid act better than soap solution and detergent solution

which can be determined by cleaning the test cloth strips that soaked with tomato sauce. As the

conclusion, between the soap and synthetic detergent, the synthetic detergent was more effective

than the soaps.


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Recommendations

When taking measurement, make sure to take the mass as accurate as possible.

When using the pH meter, make sure to clean the tips properly to avoid errors to the

reading.

References

http://www.detergentsandsoaps.com/soaps-detergents.html http://dwb4.unl.edu/chemistry/labs/LABS12.html

Chem Lab (Soaps)

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