HClO_{4 }→ **strong acid**

$\overline{){\mathbf{pH}}{\mathbf{=}}{\mathbf{-}}{\mathbf{log}}\mathbf{[}\mathbf{strong}\mathbf{}\mathbf{acid}\mathbf{]}}$

$\mathbf{pH}\mathbf{=}\mathbf{-}\mathbf{log}\mathbf{[}\mathbf{0}\mathbf{.}\mathbf{040}\mathbf{}\mathbf{M}\mathbf{]}$

**pH = 1.398 ***(same pH as **CCl _{3}CO_{2}H)*

Remember that ** weak acids** partially dissociate in water and that

The dissociation of CCl_{3}CO_{2}H is as follows:

CCl_{3}CO_{2}H(aq) + H_{2}O(l) ⇌ H_{3}O^{+}(aq) + CCl_{3}CO_{2}^{–}(aq)

**ICE Table:**

** K_{a} expression**:

$\overline{){{\mathbf{K}}}_{{\mathbf{a}}}{\mathbf{=}}\frac{\mathbf{products}}{\mathbf{reactants}}{\mathbf{=}}\frac{\mathbf{\left[}{\mathbf{H}}_{\mathbf{3}}{\mathbf{O}}^{\mathbf{+}}\mathbf{\right]}\mathbf{\left[}{\mathbf{CCl}}_{\mathbf{3}}{{\mathbf{CO}}_{\mathbf{2}}}^{\mathbf{-}}\mathbf{\right]}}{\mathbf{\left[}{\mathbf{CCl}}_{\mathbf{3}}{\mathbf{CO}}_{\mathbf{2}}\mathbf{H}\mathbf{\right]}}}$

Solving for **[H _{3}O^{+}]** from pH:

$\overline{){\left[}{{H}}_{{3}}{{O}}^{{+}}{\right]}{\mathbf{=}}{{\mathbf{10}}}^{\mathbf{-}\mathbf{pH}}}$

${\mathbf{\left[}}{{\mathbf{H}}}_{{\mathbf{3}}}{{\mathbf{O}}}^{{\mathbf{+}}}{\mathbf{\right]}}\mathbf{=}{\mathbf{10}}^{\mathbf{-}\mathbf{1}\mathbf{.}\mathbf{398}}$

**[H _{3}O^{+}] **

Trichloroacetic acid (CCl_{3}CO_{2}H) is a corrosive acid that is used to precipitate proteins. The pH of a 0.050-M solution of trichloroacetic acid is the same as the pH of a 0.040-M HClO_{4} solution. Calculate K_{a} for trichloroacetic acid.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Weak Acids concept. If you need more Weak Acids practice, you can also practice Weak Acids practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Costanza's class at USF.

What textbook is this problem found in?

Our data indicates that this problem or a close variation was asked in Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition. You can also practice Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition practice problems.