Distinguish between polyunsaturated vegetable oil and petroleum oil

In summary: The hydrogen taken up is directly proportional to the number of unsaturated bonds, so you could even use the method to quantify the amount of unsaturation in the sample.In summary, there are several chemical reactions that could be used to distinguish between polyunsaturated vegetable oil and petroleum oil containing a mixture of saturated and unsaturated hydrocarbons. These include addition of bromine in CCl4, hydrogenation, saponification, and ozonolysis. However, the most effective method would be quantitative hydrogenation, as it can accurately measure the amount of unsaturation in a sample of oil. This method involves measuring the amount of hydrogen taken up by the oil, with vegetable oils taking up significantly more than petroleum oils.
  • #1
xiaofupo
2
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1. Which of the following chemical reaction could be used to Distinguish between polyunsaturated vegetable oil and petroleum oil containing a mixture of saturated and unsaturated hydrocarbon?
Explain your answer.

i.addition of bromine in CCl4
ii. hydrogenation
iii.saponification
iv.ozonolysis

2.The attempt at solution:

i.addition of bromine in CCl4

polyunsaturated oil will be becomes colourless; whereas saturated and unsaturated mixture hydrocarbon will not become colorless

ii. hydrogenation

polyunsaturated oil becomes solidified after treated with Hydrogen , whereas saturated and unsaturated mixture hydrocarbon will not become solidified

iii.saponification

polyunsaturated oil will produce 3 unsaturated fatty acid, whereas saturated and unsaturated mixture hydrocarbon form a mixture of saturated and unsaturated fatty acid
 
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  • #2
xiaofupo said:
1. Which of the following chemical reaction could be used to Distinguish between polyunsaturated vegetable oil and petroleum oil containing a mixture of saturated and unsaturated hydrocarbon?
Explain your answer.

i.addition of bromine in CCl4
ii. hydrogenation
iii.saponification
iv.ozonolysis

2.The attempt at solution:

i.addition of bromine in CCl4

polyunsaturated oil will be becomes colourless; whereas saturated and unsaturated mixture hydrocarbon will not become colorless

No. You know nothing about the color of the petroleum oil... before or after treatment with bromine. The color of vegetable oils would come from carotenoids perhaps but you don't know if the veggie oil has been refined and is therefore initially colorless or nearly so.

ii. hydrogenation

polyunsaturated oil becomes solidified after treated with Hydrogen , whereas saturated and unsaturated mixture hydrocarbon will not become solidified

How do you know that petroleum unsaturate won't crystallize? You are correct in that it does tend to be true that petroleum unsaturates won't solidify but it isn't a definitive test.

iii.saponification

polyunsaturated oil will produce 3 unsaturated fatty acid, whereas saturated and unsaturated mixture hydrocarbon form a mixture of saturated and unsaturated fatty acid
Do petroleum oils contain triglycerides or esters?
 
  • #3
I assume by "petroleum oil" they are referring to either a paraffinic or naphthenic mineral oil. These do not contain triglycerides or esters, they are a mixture of paraffinic and naphthenic hydrocarbons, with somewhere between 0 and 15% aromatic hydrocarbons. There may also be some very minor concentrations of polar species (nitrogen or sulphur containing molecules) but this is very minor (<0.5%).

I would suggest that some form of quantitative hydrogenation would be a good way to distinguish the two. It is possible to measure the amount of hydrogen taken up by a sample of oil using a pressure-drop method, converting back to STP. You will find that a petroleum oil takes up virtually nothing, whereas a veg oil takes up about 0.1 - 0.2 cc of hydrogen per gram of oil.
 

FAQ: Distinguish between polyunsaturated vegetable oil and petroleum oil

Question 1: What is the main difference between polyunsaturated vegetable oil and petroleum oil?

Polyunsaturated vegetable oil and petroleum oil are both types of oils that are commonly used in cooking and other industrial applications. The main difference between them is their source and composition.

Question 2: Where does polyunsaturated vegetable oil come from?

Polyunsaturated vegetable oil is derived from plants such as soybeans, sunflowers, canola, and corn. These oils are extracted from the seeds of these plants through a process of pressing and refining.

Question 3: How is petroleum oil produced?

Petroleum oil, also known as crude oil, is a fossil fuel that is formed from the remains of plants and animals that lived millions of years ago. It is extracted from underground reservoirs through drilling and then refined into various products, including different types of oils.

Question 4: What is the difference in composition between polyunsaturated vegetable oil and petroleum oil?

Polyunsaturated vegetable oil is primarily composed of fatty acids, which are essential for human health. These oils contain a high proportion of polyunsaturated fats, which have been linked to various health benefits. On the other hand, petroleum oil is made up of hydrocarbons, which are not essential for human health and can even be harmful if consumed in large amounts.

Question 5: Can polyunsaturated vegetable oil and petroleum oil be used interchangeably?

No, polyunsaturated vegetable oil and petroleum oil have different properties and cannot be used interchangeably. Polyunsaturated vegetable oil has a lower smoke point than petroleum oil, which means it cannot be used for high-temperature cooking. Additionally, polyunsaturated vegetable oil has a distinct flavor and aroma, making it unsuitable for certain recipes that require a neutral-tasting oil.

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