Experiment 5: Lipids

Title: Experiment Using Lipids

Abstract:

Lipid is a diverse group of organic compounds including fats, oils, hormones, and certain components of membranes that are grouped together because they do not interact appreciably with water. The objectives of the experiment are to know the saponification number of palm oil, corn oil and sunflower oil and it application which is soap making. Reflux condenser was used for the first experiment and the saponification number was calculated. The mixture of fat and NaOH was stirred and undergo boiling process. The results were obtained where the saponification of palm oil is 14.0g, corn oil 71.5g and sunflower oil is 112.2g. The soap was produced from palm oil. From the results the sunflower oil has the highest saponification number followed by corn oil and the lowest is palm oil. 

 Introductions:

The lipids are a large and diverse group of naturally occurring organic compounds that are related by their solubility in nonpolar organic solvents (e.g. ether, chloroform, acetone & benzene) and general insolubility in water. There is great structural variety among the lipids, as will be demonstrated in the following sections. Lipids are found to be water insoluble but they are found to be soluble in fat solvent. They are heterogeneous group of fatty acids.  They include fats, oils, waxes and other related substances.  They are oily or greasy substances.  Thus they are hydrophobic in nature. Proteins, polysaccharides, DNA and RNA are macromolecules.  Lipids are not generally classed as macromolecules, even though they share some features of macromolecules.  For example: lipids synthesized as linear polymers and they self assemble into larger structures.t heir primary purpose in the body is energy storage- a very small mass of lipids can store a very large amount of energy, which is excellent if you don't happen to have a ready energy supply around. In adipose tissue, lipids can also serve as cushioning.

         Saponification is  a process by which triglycerides are reacted with sodium or potassium hydroxide to produce glycerol and a fatty acid salt, called 'soap'. Lipids that contain fatty acid ester linkages can undergo hydrolysis. This reaction is catalyzed by a strong acid or base. Saponification is the alkaline hydrolysis of the fatty acid esters.

Methods:

1. Saponification of triglycerides

2. Application :Making soap

Results:
1. Saponification of Triglycerides

Sample	Initial volume of HCl  blank -  Final volume of HCl blank (in liter)	Initial volume of HCl sample – Final volume of HCl sample (in liter)	Mol for blank (mol) x Volume of HCl (blank)	Mol for sample (mol) x Volume of HCl (sample)	Mol of reacted KOH	Saponification number = Mol of KOH x 56.1 x (in gram)
Palm oil	0.025	0.0245	0.0125	0.01225	0.0003	14.0
Corn oil	(0.026 + 0.028) / 2 Average = 0.027	(0.024 + 0.025) / 2 Average = 0.025	(0.013 + 0.014) / 2 Average = 0.014	(0.012 + 0.0123) / 2 Average = 0.012	(0.001 + 0.002) / 2 Average = 0.002	(56.1 + 86.9) / 2 Average = 71.5
Sunflower oil	(0.027 + 0.027)/ 2 Average = 0.027	(0.022 + 0.025) / 2 Average = 0.024	(0.014 + 0.013) / 2 Average = 0.014	(0.011 + 0.0123) / 2 Average = 0.012	(0.003 + 0.001) / 2 Average = 0.002	(168.3 + 56.1) / 2 Average = 112.2

2. Application: Making Soap

Discussion: 

Saponification is the hydrolysis of an ester under basic conditions to form an alcohol and the salt of a carboxylic acid. Saponification is commonly used to refer to the reaction of a metallic alkali or base with a fat or oil to form soap.  In the experiment, by heating a triglyceride in aqueous sodium hydroxide (NaOH) the fatty acyl esters can be cleaved off by process called hydrolysis leaving behind glycerol and the sodium salt of the fatty acid. Saponifiable substances are those that can be converted into soap.

According to the experiment that has been conducted, we did get the result for liquid saponification number of several samples such as palm oil, sunflower oil, and also corn oil. Here, our experimental result indicate that  sunflower oils shows the highest number of saponification which is 112.2 gram of fat as compared to the corn oil (71.5 gram of fats) and palm oil (14.0 gram of fat). But, it supposed to be the palm oil has the greater saponification number based on theoretical result then followed by corn oil and sunflower oil. This experiment error is may be due to the improper wash of the distillation flask and we did not dry it well before reuse it again for obtaining the blank reading later on. Unfortunately, the residues of the sample may be still left behind in the distillation flask.

            Chemical reaction such as saponification, it is necessary for the reactants to be in the same phase. Hydroxide will almost entirely exist in the aqueous phase (NaOH solution), and the triglyceride will be almost entirely in the organic phase. In the experiment, increasing stirring will create more interfaces for the reaction to proceed. And, as the reaction goes, it will be producing glycerin and fatty acid salts, which can have appreciable solubility in both phases. So, the reagents will increase in concentration in the phase most favored by the other as the reaction progresses.

            Saponification value represents the number of milligrams of sodium hydroxide required to saponify one gram of fat under the conditions specified. It is a measure of the average molecular weight or chain length of all the fatty acids present. As most of the mass of a fat is in the three fatty acids, it allows for comparison of the average fatty acid chain length. The saponification number was used as an indicator of fatty acid chain length in triglycerides. The value is simply a measurement of the volume of NaOH required to complete the hydrolysis of one gram of fat or oil. If the triglyceride contains low molecular weight fatty acids, the number of molecules present in a one gram of the fat will be greater than if the fatty acids have long carbon chains and high molecular weights, resulting for the fat with the low molecular weight fatty acids to have a higher saponification number.

            There is a difference in the molar of HCl used to neutralize the control (blank) and the amount of HCl used to neutralize the sample that is equivalent to the amount of KOH needed to saponify the test sample. The proof reason is because in this experiment 0.5 mol of HCl has been react with 0.5 mol of KOH. Therefore, the sample of test will require more acid, HCl to neutralize it because of the higher alkali content as compare to the control (blank). Since it is 1:1 reaction, the moles for both HCl and KOH are equivalent.

            Soap is an excellent cleanser because of its ability to act as an emulsifying agent. An emulsifier is capable of dispersing one liquid into another immiscible liquid. Nearly all compounds fall into one of two categories which are hydrophilic and hydrophobic. Water and anything that will mix with water are hydrophilic. Oil and anything that will not mix with water are hydrophobic. When water and oil are combined together, they tend to be separated, that is why hydrophilic and hydrophobic compounds just do not mix. When grease or oil is mixed with a soap water solution, the soap molecules work as a bridge between polar water molecules and non-polar oil molecules. The higher the concentration of the reactants, the more opportunity they have to react and the faster the reaction will go.

References:

Lipids . Retrieved on May 20, 2013 from http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/lipids.htm   

Lipids. Retrieved on May 20, 2013 from http://biosiva.50webs.org/lipids.htm

Lipid. Retrieved on May 20, 2013 from http://en.wikipedia.org/wiki/Lipid

Preparation of soap. Retrieved on May 20, 2013 from http://www.laney.edu/wp/cheli-fossum/files/2012/01/13-Saponification.pdf