a solution is made up of 0.001M dichloroacetic and 0.0001M acetic acid.find the pH using the charge balance
To find the pH using the charge balance, we need to consider the dissociation of both the dichloroacetic acid (DCA) and acetic acid.
Dichloroacetic acid (DCA): DCA can dissociate into its conjugate base, dichloroacetate ion (DCA-), and release a hydrogen ion (H+).
DCA ⇌ DCA- + H+
Acetic acid: Acetic acid can dissociate into its conjugate base, acetate ion (CH3COO-), and release a hydrogen ion (H+).
CH3COOH ⇌ CH3COO- + H+
We are given the concentrations of 0.001 M for DCA and 0.0001 M for acetic acid.
To solve, we need to consider the charge balance equation for the solution:
[H+] + [DCA-] + [CH3COO-] = [OH-]
Since the solution is aqueous, we assume the concentration of hydroxide ions (OH-) to be negligible compared to the other ions.
Thus, the equation simplifies to:
[H+] = [DCA-] + [CH3COO-]
First, let's calculate the concentrations of DCA- and CH3COO- using the given concentrations.
[DCA-] = [DCA] = 0.001 M
[CH3COO-] = [acetic acid] = 0.0001 M
Now, substitute these values into the charge balance equation:
[H+] = 0.001 M + 0.0001 M
[H+] = 0.0011 M
The pH of a solution is calculated by taking the negative logarithm (base 10) of the hydrogen ion concentration ([H+]).
pH = -log10([H+])
pH = -log10(0.0011)
pH ≈ 2.96
Therefore, the pH of the solution is approximately 2.96.