what is the concentration of a weak acid with a pH of 3.25, if the Ka of the weak acid is 1.6 x 10^-7 ?
pH = -log(H^+)
-3.25 = log(H^+)
(H^+) = 5.62E-4
............HA ==> H^+ + A^-
initial.....x.......0.....0
equil.......x...5.62E-4..5.62E-4
Ka = (H^+)(A^-)/(HA)
Substitute (H^+), (A^-) and Ka, and solve for (HA) = x
6.0x10-3
To find the concentration of a weak acid given its pH and the Ka value, you can start by using the equation for calculating the pH of a weak acid:
pH = -log[H+]
Since we have the pH value (3.25), we can rearrange the equation to solve for [H+]:
[H+] = 10^(-pH)
[H+] = 10^(-3.25)
[H+] = 5.01 x 10^(-4)
Now, we know that for a weak acid, the concentration of the acid is equivalent to the concentration of [H+]. Therefore, the concentration of the weak acid with a pH of 3.25 is 5.01 x 10^(-4) M.