# chemistry

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. 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.

posted by DrBob222
2. got it!
ka= 3.26*10^-3
so pKa=2.49

tnx

posted by Will

## Similar Questions

1. ### chemistry

A 1.0 x 10-2 M solution of a weak acid is found to be 3.7% dissociated. Calculate Ka of this acid. I found the amount dissociated by (amount dissociated/initial conc)*100=3.7 Where do I go from here?
2. ### chemistry

In a .25 M solution, a weak acid is 3.0% dissociated. A. calculate the pH of the solution B. calculate the Ka of the acid Please explain steps.
3. ### Chemistry

A 0.39 M solution of a weak acid is 3.0% dissociated. Calculate Ka.
4. ### chemistry

a 0,25M solution of a week acid is 3% dissociated.calculate ka
5. ### Chemistry

What is the hydrogen ion concentration in a 0.15 molar solution of acetic acid in water at 25 degrees C? Acetic acid is 1.3 % dissociated.
6. ### chemistry

a 205 mg sample of diprotic acid is dissolved in enough water to make 250 ml of solution. The pH of this solution is 2.15. A saturated solution of calcium hyrdoxide (Ksp=1.3*10^-6) is prepared by adding excess calcium hydroxide to
7. ### Chemistry

A 205 mg sample of a diprotic acid is dissolved in enough water to make 250.0 ml of solution. The pH of this solution is 2.15. A saturated solution of calcium hydroxide (Ksp= 1.3 x 10-6) is prepared by adding excess calcium
8. ### chem

calculate the mass in grams of oxygen atoms in 0.25 mol fluoroacetic acid
9. ### chem

calculate the number of oxygen atoms in 0.25 mol fluoroacetic acid (C2H3O2F) show work if possible
10. ### chemistry

2- A 0.310 M solution of a weak acid, HX, has a pH of 2.53 a. Find the [H+] and the percent ionization of nitrous acid in this solution. b. Write the equilibrium expression and calculate the value of Ka for the weak acid. c.

More Similar Questions