Experiment 8: Fats & Oils Flashcards
Fats and oils, which are principally high-molecular weight esters, are known collectively as _____
Lipids
Fats and oils as esters are called ______
Triglycerides
What are fats and oils formed from?
- Higher fatty acids
- Glycerol (trihydric alcohol)
The molecular structure of lipids is composed of:
- 1 molecule of Glycerol
- 3 molecules of Fatty Acid
What four oils were used in the experiment, and what were their colors?
- Coconut oil: golden yellow
- Cottonseed oil: pale yellow
- Olive oil: pale yellow
- Linseed oil: dark orange
A.1. What is Miscibility?
Miscibility is the property of two liquid substances to mix in all proportions, forming a homogeneous mixture.
A liquid dissolves completely in another liquid
A.2. Miscibility Test process:
Coconut, cottonseed, olive, and linseed oils are added to:
- H2O
- C2H5OH / ethyl alcohol
- CHCl3 / chloroform
A.3. Results of oils with H2O, and why:
Oils did not mix with H2O, thus are immiscible with water.
This is because H2O is a polar molecule, and the oils are non-polar, making them incompatible
A.4. Results of oils with C2H5OH:
Oils only slightly mixed with ethyl alcohol, thus may be considered either miscible or immiscible
A.3. Results of oils with CHCl3, and why:
Oils completely dissolved in CHCl3, thus are miscible
This is because all substances were non-polar, which results in 100% miscibility.
A.4. What are Polar & Non-Polar molecules?
Polar molecules have ends that aren’t the same due to uneven distribution of charge across their geometry resulting in one side being positive and the other side negative.
Non-polar are similarly charged at both ends.
B.1. It is the standard chemical test for fats and glycerol.
Acrolein Test
B.2. Acrolein Test process:
(1) Coconut oil, (2) CH2OH-CHOH-CH2OH or Glycerol + KHSO4 or Potassium bisulfate
Boil
B.3. What is the function of KHSO4 in Acrolein Test?
It is the hydrolyzing, dehydrating & oxidizing agent
B.4. What is the characteristic result of Acrolein Test, and what does it indicate?
A foul odor is emitted, indicating the presence of oxidized glycerol or Acrolein / CH2=CH-CHO
B.5. What is Acrolein and how was it formed?
Acrolein or CH=CH-CHO is an unsaturated aldehyde formed by dehydrating & oxidizing the oil’s glycerol part
B.6. How was Acrolein formed?
- KHSO4 hydrolyses lipid, breaking them down into fatty acid & glycerol components.
- The expelled CH2OH-CHOH-CH2OH is dehydrated and oxidized by KHSO4, leading to the formation of Acrolein.
C.1. Fats and oils usually have _____ & _____ bonds
Conjugated & double
C.2.Unsaturation Test process:
Coconut, cottonseed, olive, and linseed oils are added to alcoholic I2
C.3. Unsaturation Test involves addition reactions, sepcifically _____
Halogenation
C.4. Why is Iodine used to test for unsaturation?
Unsaturation occurs mainly as double bonds which are very reactive towards halogens, the iodine in this case. Thus, the higher the iodine value, the more unsaturations are present in the oil.
C.5. Colors of the oil with alcoholic Iodine:
Linseed: vibrant bright orange
Cottonseed: bright yellow
Olive & Coconut: dark orange
C.6. Oil unsaturation ranking:
- Linseed - absorbed the most I2
- Cottonseed
- Olive
- Coconut - the most saturated
D.1. What is Saponification?
Any reaction of an ester with a base or alkali in water to produce an alcohol & acid salt
D.2. Saponification process:
(C11H23COOCH2)2-C11H23COOCH or Coconut oil + NaOH
- Heat mixture
- Stir until mixture sticks to stirring rod
- Pour in matchbox
D.3. What is the purpose of NaOH in Saponification?
It is the alkali that hydrolyzes the coconut oil
D.4. What is formed from the Saponification of Coconut oil? What is its equation:
- Metallic soap or 3 C11H23COONa
- Glycerol or CH2OH-CHOH-CH2OH
Equation:
(C11H23COOCH2)2-C11H23COOCH + 3 NaOH -> C11H23COONa + CH2OH-CHOH-CH2OH
D.5. How was the metallic soap formed?
- NaOH hydrolyzes the coconut oil, breaking it into glycerol and fatty acids
- NaOH then reacts with the freed fatty acids to form the metallic soap
D.6. What was the name of the formed soap?
Sodium laurate / C11H23COONa
