We're asked to **d****etermine the pH of a solution that is 1.07% HCl by mass.**

Recall that the pH of a solution is given by:

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

Take note that: **[H ^{+}] = [H_{3}O^{+}]**

Since **HCl is a strong acid**, it will *completely dissociate into ions* in solution as follows:

HCl(aq) → H^{+}(aq) + Cl^{–}(aq)

This means that: **[HCl] = [H ^{+}]**

***Brackets, [] indicate concentration in molarity*

We first need to determine the molarity of HCl.

Recall that ** molarity (M)** is given by:

** **

$\overline{){\mathbf{Molarity}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\frac{\mathbf{mol}\mathbf{}\mathbf{solute}}{\mathbf{L}\mathbf{}\mathbf{solution}}}$

Since we’re given the mass percent* (% by mass)* and the density of HCl solution, we can find the number of moles of HCl and the volume of the solution.

Recall that ** mass percent** is given by:

$\overline{){\mathbf{m}}{\mathbf{a}}{\mathbf{s}}{\mathbf{s}}{\mathbf{}}{\mathbf{p}}{\mathbf{e}}{\mathbf{r}}{\mathbf{c}}{\mathbf{e}}{\mathbf{n}}{\mathbf{t}}{\mathbf{}}{\mathbf{=}}\frac{\mathbf{m}\mathbf{a}\mathbf{s}\mathbf{s}\mathbf{}\mathbf{s}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{t}\mathbf{e}}{\mathbf{m}\mathbf{a}\mathbf{s}\mathbf{s}\mathbf{}\mathbf{s}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{t}\mathbf{i}\mathbf{o}\mathbf{n}}{\mathbf{\times}}{\mathbf{100}}}$

Determine the pH of each solution.

a solution that is 1.07% HCl by mass (Assume a density of 1.01 g / mL for the solution.)

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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 Strong Acid-Base Calculations concept. If you need more Strong Acid-Base Calculations practice, you can also practice Strong Acid-Base Calculations practice problems.

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