AlF3 is almost insoluble in anhydrous HF but dissolves if KF is present.passage of BF3 through the resulting solution causes AlF3 to precipitate... can anyone explain the idea behind this?

Question

abb0t · Answer

AlF3 doesn't dissolve in HF because of the fluorine. It's doesn't allow for coordination due to the hydrogen. However, it will dissolve in KF. If you look at the chemical reaction, it's able to form a salt!

$$3 KF + AlF_3 -> 3 KF.AlF_3$$

However, when BF3 is added
$$3 KF.AlF_3 + 3 BF_3 -> AlF_3(s) + 3 KBF_4 $$

anonymous · Answer

can u pls explain ur first 2 statements.... i want a detailed answer...

abb0t · Answer

H-F is a pretty strong bond compared to K-F.

anonymous · Answer

yeah right! thankx

abb0t · Answer

Not much I can use to describe this w/o going outside the scope of general chemistry.

anonymous · Answer

ya pretty difficult...

abb0t · Answer

The best explanation is with a chemical reaction. In an inorganic chemistry course, the explanation I gave would be detailed enough. To be more specific, it's b/c the product formed with BF3 is more complex. able to decompose AlF3