Cracking of hydrocarbons and boiling point of salt water

In summary, alkenes can also be cracked, resulting in the formation of propene and ethene. In distillation, when combining immiscible liquids like water and alkanes/alkenes, the total vapor pressure of the mixture is lower than the boiling points of the individual liquids. This is due to the stirring of the mixture.
  • #1
sgstudent
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Can alkenes be cracked or only alkanes can be cracked? Then what would the products be? Like for alkanes a alkenes must always be formed but what about for alkenes cracking?

Also, when we boil salt water its temperature is 101.4 degrees. But when performing fractional or simple distillation why dots the reading at the thermometer be 100 degrees even though the boiling point is 101.4?

Thanks for the help guys! :smile:
 
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  • #2
Alkenes can be cracked as well. An example would be cracking butene to yield propene and ethene.

As for distillation, when you combine two immiscible liquids (such as water and alkanes/alkenes), the total vapor pressure of the mixture is the sum of the vapor pressures of the different liquids in the mixture. The result of this is that, as long as the mixture is being stirred, the boiling point of the mixture will be lower than the boiling points of any of the liquids if they were pure.
 
  • #3
Jasoni22 said:
when you combine two immiscible liquids (such as water and alkanes/alkenes), the total vapor pressure of the mixture is the sum of the vapor pressures of the different liquids in the mixture. The result of this is that, as long as the mixture is being stirred, the boiling point of the mixture will be lower than the boiling points of any of the liquids if they were pure.

I don't see how it addresses the question, NaCl is not a liquid immiscible with water.
 
  • #4
I was assuming that the distillation was of hydrocarbons mixed in water, since you wouldn't perform fractional distillation of mere salt water with nothing else in it.
 
  • #5


I can provide an explanation for the cracking of hydrocarbons and the boiling point of salt water.

Firstly, both alkanes and alkenes can undergo cracking, which is the process of breaking down larger hydrocarbon molecules into smaller ones. This is typically done through high temperatures and pressure, and can result in the formation of alkenes, alkanes, and other byproducts. However, the products formed from cracking will depend on the specific conditions and reactants involved.

In terms of boiling point, it is important to note that salt water is a mixture of water and salt (sodium chloride). The boiling point of pure water is 100 degrees Celsius, but when salt is added, the boiling point of the mixture increases. This is because the presence of salt disrupts the intermolecular forces between water molecules, making it harder for them to escape as vapor.

When performing fractional or simple distillation, the thermometer reading will still be at 100 degrees Celsius because the thermometer is measuring the temperature at which the water component of the mixture is boiling. The salt is not boiling, but rather remaining in the solution. Therefore, the thermometer reading will not change even though the boiling point of the mixture is higher due to the presence of salt.

I hope this helps to clarify any confusion. Remember, as a scientist, it is important to always carefully consider the conditions and reactants involved in any chemical process in order to accurately predict the products and outcomes.
 

1. What is the process of cracking hydrocarbons?

The process of cracking hydrocarbons involves breaking down larger molecules of hydrocarbons into smaller, more useful ones. This is typically done by applying heat and pressure to the hydrocarbons, which causes the bonds between the molecules to break and form new ones. This process is used to produce a variety of products, including gasoline, diesel, and other fuels.

2. How does the boiling point of salt water differ from that of pure water?

The boiling point of salt water is higher than that of pure water. This is because the salt in the water raises the boiling point by increasing the boiling point elevation. This means that it takes more energy to reach the boiling point of salt water compared to pure water.

3. What causes hydrocarbons to crack?

Hydrocarbons are cracked due to the high temperatures and pressures that are applied during the process. This causes the bonds between the molecules to break, leading to the formation of smaller molecules. The process of cracking is also known as thermal decomposition.

4. What are the main products of cracking hydrocarbons?

The main products of cracking hydrocarbons are smaller molecules of hydrocarbons, such as ethane, propane, and butane. These molecules are used as fuels in various industries, including transportation and heating. Other products that may be produced during cracking include ethylene, propylene, and butadiene, which are used in the production of plastics and other materials.

5. How is the cracking of hydrocarbons used in the petroleum industry?

The cracking of hydrocarbons is a crucial process in the petroleum industry as it allows for the production of various valuable products. This process is used to convert heavy crude oil into lighter, more valuable products such as gasoline and diesel. Cracking also helps to increase the overall yield of usable products from crude oil, making the refining process more efficient.

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