Why add ethanol in step 5?

In summary, ethanol is added in step 5 to create a homogeneous mixture which is less polar than water alone. This causes the salt to become less soluble and precipitate out.
  • #1
jsmith613
614
0

Homework Statement




what is the purpose of adding ethanol in step 5 in the following description?

http://www.creative-chemistry.org.uk...s/N-ch5-08.pdf [Broken]

Homework Equations




The Attempt at a Solution


Does adding ethanol make the liquid phase (which is now a homogenous mixture) less polar because ethanol is slighly hydrophobic hence the salt is less soluble so precipitates out?
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
Link is broken.

But your explanation is more or less what could be expected.
 
  • #3
Borek said:
Link is broken.

But your explanation is more or less what could be expected.

http://www.creative-chemistry.org.uk/alevel/module5/documents/N-ch5-08.pdf
 
  • #4
I don't think calling ethanol hydrophobic is the best approach. It has a lower dielectric constant and because of its size it is not as effective at solvation, so it doesn't isolate ions as effectively as water does.
 
  • #5
Borek said:
I don't think calling ethanol hydrophobic is the best approach. It has a lower dielectric constant and because of its size it is not as effective at solvation, so it doesn't isolate ions as effectively as water does.

would it please be possible then to give me an A2 level answer (i don't know about dielectric constant) that would gain 1 or 2 marks?

thanks
 
  • #6
Borek said:
I don't think calling ethanol hydrophobic is the best approach. It has a lower dielectric constant and because of its size it is not as effective at solvation, so it doesn't isolate ions as effectively as water does.

would the following be better:

"the homogeneous mixture of ethanol and water is less polar that water alone so the salt is less soluble and hence precipitates out
 
  • #7
jsmith613 said:
the homogeneous mixture of ethanol and water is less polar that water alone so the salt is less soluble and hence precipitates out

Sounds good to me.
 

1. What is ethanol-salt precipitation?

Ethanol-salt precipitation is a process used to separate nucleic acids, proteins, and other macromolecules from a solution using ethanol and salt. This process takes advantage of the fact that these molecules are less soluble in a high concentration of ethanol and salt, causing them to form a precipitate that can be easily separated from the solution.

2. How does ethanol-salt precipitation work?

Ethanol-salt precipitation works by adding a high concentration of ethanol and salt to a solution containing the desired molecules. This high concentration of ethanol and salt causes the molecules to become less soluble and form a precipitate, which can then be separated from the solution by centrifugation or filtration.

3. What is the purpose of using ethanol-salt precipitation in research?

Ethanol-salt precipitation is commonly used in research to isolate and purify nucleic acids and proteins from a solution. This technique is useful for removing impurities and concentrating the desired molecules, making them easier to work with and analyze.

4. Are there any limitations to using ethanol-salt precipitation?

One limitation of using ethanol-salt precipitation is that it may not be effective for separating all types of macromolecules. For example, some proteins may not precipitate in high concentrations of ethanol and salt, making this technique less useful for purifying them. Additionally, the precipitate formed may contain impurities that can affect downstream experiments.

5. Are there any safety concerns when working with ethanol-salt precipitation?

Ethanol-salt precipitation typically involves handling high concentrations of ethanol, which can be flammable and irritant to the skin and eyes. It is important to follow proper safety procedures, such as wearing gloves and eye protection, when performing this technique in the laboratory.

Similar threads

  • Biology and Chemistry Homework Help
Replies
3
Views
3K
  • Biology and Chemistry Homework Help
Replies
2
Views
8K
  • Biology and Chemistry Homework Help
Replies
2
Views
5K
  • Biology and Chemistry Homework Help
Replies
2
Views
5K
  • Sci-Fi Writing and World Building
Replies
21
Views
856
Replies
4
Views
3K
Back
Top