Short question (1 Viewer)

[bleakarcher]

Why do CFCs and HCFCs have low to no solubility in water?

Thanks

 

[someth1ng]

For CFCs:
Chlorine and fluorine have relatively close electronegativities - ~4 vs ~3.5, IIRC. When you have them around a central carbon atom, this causes the dipoles from C-Cl and C-F bonds to cancel out. There will be some polarity left but it will be quite limited and hence, it is largely non-polar.

For HCFCs:
Similar to above but you also have hydrogen - C-H, C-Cl and C-F bonds can all cancel each other out to some extent (not completely, though) as they are arranged opposite to each other causing dipoles to cancel out. HFCs, due to the presence of hydrogen, are a bit more polar than similar CFCs.

Now that I have covered why it is non-polar, you can now go on to say that since they are relatively non-polar, they will have limited solubility in water because water is polar and generally, polar dissolves in polar and non-polar dissolves in non-polar.

 

[HeroicPandas]

why cant CFCs such as interact with water molecules through dipole-dipole interactions? (i.e. the electropositive hydrogen of water molecules attract to the CFC)

 

[someth1ng]

why cant CFCs such as interact with water molecules through dipole-dipole interactions? (i.e. the electropositive hydrogen of water molecules attract to the CFC)

How is hydrogen electropositive? That's really only the case when it is bonded to something that's very electronegative like oxygen, fluorine and nitrogen.

Between hydrogen and carbon, the electrons are relatively equally shared.

 

[HeroicPandas]

How is hydrogen electropositive? That's really only the case when it is bonded to something that's very electronegative like oxygen, fluorine and nitrogen.

Between hydrogen and carbon, the electrons are relatively equally shared.

sorry for the lack of clarity!

Here is what is in my head:

Water (H2O) possess an electropositive hydrogen

CF3Cl (a CFC) comes close and shows off its electronegativity



^A display of dipole-dipole attraction, so water and the CFC interact thus dissolving the CFC

wrong or right?

 

[someth1ng]

sorry for the lack of clarity!

Here is what is in my head:

Water (H2O) possess an electropositive hydrogen

CF3Cl (a CFC) comes close and shows off its electronegativity



^A display of dipole-dipole attraction, so water and the CFC interact thus dissolving the CFC

wrong or right?

As I previously covered, H2O is polar and CFCs are largely non-polar (only slightly polar) and hence, it will only dissolve slightly in water.

Now, the reason why non-polar and polar molecules are not miscible with each other is for this reason - it is not well covered in HSC or even uni. We'll use water and oil as an example.
Water is very polar and hence, its bonds between each other are very strong. Oil is very non-polar and hence, its bonds between each other are weaker. As dipole-dipole bonds are stronger, there will be a tendency for them to occur more - thus, water will try to stick to itself. This leave the oil to only bond with itself.

As a general rule, things will try to form the strongest bonds because this will ultimately result in the lower or lowest energy state.

 

[HeroicPandas]

As I previously covered, H2O is polar and CFCs are largely non-polar (only slightly polar) and hence, it will only dissolve slightly in water.

Now, the reason why non-polar and polar molecules are not miscible with each other is for this reason - it is not well covered in HSC or even uni. We'll use water and oil as an example.
Water is very polar and hence, its bonds between each other are very strong. Oil is very non-polar and hence, its bonds between each other are weaker. As dipole-dipole bonds are stronger, there will be a tendency for them to occur more - thus, water will try to stick to itself. This leave the oil to only bond with itself.

As a general rule, things will try to form the strongest bonds because this will ultimately result in the lower or lowest energy state.

ok thanks, all i needed to hear was "only dissolve slightly in water" lol