# chemistry

posted by WIll

A 1.11 M solution of fluoroacetic acid, FCH2CO2H, is 5% dissociated in water. Calculate the value of the pKa of FCH2CO2H.

pKa:

?? I dn't even know how to strt with this

1. DrBob222

Let's call fluoroacetic acid HFAc. Then
.........HFAc ==> H^+ + FAc^-
I.......1.11......0......0
C.....-0.055....0.055...0.055
E......you do it..0.055..0.055

Ka = (H^+)(FAc^-)/(HFAc)
Substitute the E line into Ka expression and solve for Ka, then convert to pKa.
Note: The acid is 5% dissociated, therefore, every 100 mols dissociates to give 5 of each ion and leaves 95 undissociated molecules. Therefore, M x 0.05% gives you the ion M and 1.11- that gives you the undissociated part.

2. Will

got it!
ka= 3.26*10^-3
so pKa=2.49

tnx

## Similar Questions

1. ### CHEM!

Okay well I suddenly got confused for a lab I did We took pH meter than we calibrate it. Then we measure the pH of the acetic acid solution, which was used to determine the Ka of the acetic acid using the first method. We made a 1M …
2. ### college chemistry

In the analysis of food, the nitrogen from the protein is sometimes converted into ammonia which is titrated against a strong acid. Given that the final NH3 concentration (approximate) is 0.2M and that pKa for NH4+ is 9.2, choose the …
3. ### CHEMISTRY

In the analysis of food, the nitrogen from the protein is sometimes converted into ammonia which is titrated against a strong acid. Given that the final NH3 concentration (approximate) is 0.2M and that pKa for NH4+ is 9.2, choose the …
4. ### Chemistry

the pka of acetone is CH3COCH3 is 19.3 which of these bases is strong enough to deprotonate acetone?
5. ### chemistry buffers

What molar ratio of HPO4 2- to H2PO4 - in solution would produce a pH of 7.0?

An unknown compound, X, is though to have a carboxyl group with a pKa of 2.0 and another ionizable group with a pKa between 5 and 8. When 75 mL of 0.1M NaOH is added to 100 mL of a 0.1M solution of X at pH 2.0, the pH increases to …