Chemistry 1046
posted by Anonymous on .
A metal, M, of atomic mass 91 amu reacts with fluorine to form a salt that can be represented as MFx. In order to determine x and therefore the formula of the salt, a boiling point elevation experiment is performed. A 9.05g sample of the salt is dissolved in 100.0 g of water and the boiling point of the solution is found to be 374.54 K. Find the formula of the salt. Assume complete dissociation of the salt in solution.
Is the answer not MF_3??

assume it is MF3. then
bpe=.52*4*9.05/(.1*(91+3*19))
bpe=18.8/(14.8)=1.2 check that.
Is that equivalent to a new bp of 374.54K? 
It is not... So where do I go from here?

You're right. It isn't MF3.
Do it this way.
delta T = i*Kb*m
If you let MFx ionize into M + xF, then
molar mass is 91+19x and
m = 90.5g/(91+19x)
Substitute delta T, for i substitute x+1, then Kb and m. Solve for x. 
the answer should be ZrF4

ZrF4 is wrong.

This is an OLD question but I'm having trouble on it... *sigh*