We’re being asked **to calculate the pH** of a mixture of a 0.110 M formic acid and 5.5x10^{-2} M hypochlorous acid.

Recall that for a **mixture of weak acids, the total [H _{3}O^{+}]** can be calculated using the following equation:

$\overline{)\mathbf{\left[}{\mathbf{H}}_{\mathbf{3}}{\mathbf{O}}^{\mathbf{+}}\mathbf{\right]}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\sqrt{{\mathbf{K}}_{{\mathbf{a}}_{\mathbf{1}}}{\mathbf{C}}_{\mathbf{1}}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{K}}_{{\mathbf{a}}_{\mathbf{2}}}{\mathbf{C}}_{\mathbf{2}}}}$

where K_{a1} is the acid dissociation constant of acid 1, C_{1} is the concentration of acid 1, K_{a2} is the acid dissociation constant of acid 2 and C_{2} is the concentration of acid 2.

The **relationship between H _{3}O^{+} and pH** is given by:

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

We will do the following steps to solve the problem:

Step 1: Calculate the total [H_{3}O^{+}] for the mixture

Step 2: Determine pH from [H_{3}O^{+}]

Find the pH of each mixture of acids.

0.110 M in formic acid and 5.5×10^{−2} M in hypochlorous 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.

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