[DiscreteW]

Determine which of the following molecules will dissolve in water:

NaCl

CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3

HOCH2CH2CH2CH2CH2OH

(Where, of course, the numbers above are subscripts).

Thanks for the help. Also, can you tell me how you come to the conclusions you do? That is, how you know which will dissolve in water?

Thanks!

[macman104]

Is water a polar or nonpolar compound?

Do you know what an ionic compound is?

[DiscreteW]

Because of water's bent shape, it is a polar molecule.

Yes, I know what an ionic compound is. The ions are held together by ionic bonds (and we know an ion is an atom that has lost/gained an electron- that is, a valence one).

[DiscreteW]

Hmm, okay, well according to Wikipedia, ionic compounds dissolve in polar solvents, and hence would dissolve in water. So, NaCl would dissolve in water. I guess this is just a given fact that you memorize? What about the others?

[azmanam]

a good rule of thumb:

like dissolves like

polar compounds typically dissolve in polar solvents.  non polar compounds typically do not dissolve in polar solvents.

of the remaining two compounds, are any of them polar?

[DiscreteW]

Um, well CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3 has the carbon and hydrogen bonds at the end, so I am assuming not since we know all carbon molecules are nonpolar.

HOCH2CH2CH2CH2CH2OH has the alcohol group at the end... I think this is polar?

[macman104]

Remember that as the carbon length increases the polarity of the molecule decreases because C-H bonds are not polar.

[nj_bartel]

1,5-pentanediol is pretty in between... it is miscible in water.