[NaCl]

I'm a Thai Student and I'm sorry for my English.

I have just studied about The Periodic Table of the Elements. In class, the teacher taught about the properties of chloride compound (for example, NaCl, CaCl₂) and she said that BCl₃ is dissoluble in water. However, I find it in a book that BCl₃ is nonpolar. Can anyone please explain me how it is dissoluble in water while it is nonpolar?

Thank you so much and Sorry again for my English...

[AWK]

Boron trichloride reacts with water! (hydrolysis)

[Donaldson Tan]

Boron in BCl₃ is electron deficient, so BCl₃ readily undergoes hydrolysis

[Mitch]

Electron deficient by empirical forumla, but not by crystal structure.

[AWK]

Electron defficient also in crystal structure

[tamim83]

Can anyone please explain me how it is dissoluble in water while it is nonpolar?

A very general rule when it comes to solubility is "like dissolves like".  This means that polar solutes will dissolve in polar solvents and nonpolar solutes will dissolve in nonpolar solvents.  BCl₃ is nonpolar, due to its molecular geometry.  Water is polar for the same reason, its molecular geometry.  Therefore BCl₃ is not soluble in water because they have different polarities.  This is the simple explaination as to why boron trichloride won't dissolve in water. 

[AWK]

Can anyone please explain me how it is dissoluble in water while it is nonpolar?

A very general rule when it comes to solubility is "like dissolves like".  This means that polar solutes will dissolve in polar solvents and nonpolar solutes will dissolve in nonpolar solvents.  BCl₃ is nonpolar, due to its molecular geometry.  Water is polar for the same reason, its molecular geometry.  Therefore BCl₃ is not soluble in water because they have different polarities.  This is the simple explaination as to why boron trichloride won't dissolve in water. 

This general rule is not applicable to BCl3 because it reacts with water and H3BO3 + HCl is in water solution. H3BO3 in the presence of strong acid is poorly soluble. But in the hypothetical case when BCl3 will not react with water it will be soluble because of complex forming with electrons of oxygen atoms, (eq methanol or diethyl ether complexes are commercially available)..

[tamim83]

OK, I did some further reading and yes boron trichloride is a "special case" since it does react with water, and quite violently too.  Also yes if not for the reactivity of it, it would still dissolve in water since it would form a complex with water, which changes its dipole moment and lets it dissolve in water.  Hmmm, I guess that rule does not really hold up always.  This kind of stuff interests me as an educator, exspecially since it does not seem that anyone taught me exceptions to like dissolves like and boron chemistry much. Interesting...