Calculate the pH of solutions prepared by: (d) Mixing 100.0 mL of 2.0 * 10-3 M HCl and 400.0 mL of 1.0 * 10-3 M HClO4. (Assume that volumes are additive.)

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Determine the total volume of the mixed solution by adding the volumes of the two solutions: 100.0 mL + 400.0 mL.

Calculate the moles of HCl in the solution using the formula: moles = concentration (M) * volume (L).

Calculate the moles of HClO4 in the solution using the same formula: moles = concentration (M) * volume (L).

Add the moles of HCl and HClO4 to find the total moles of H+ ions in the solution, since both are strong acids and fully dissociate.

Calculate the concentration of H+ ions in the mixed solution by dividing the total moles of H+ by the total volume in liters, then use the formula pH = -log[H+] to find the pH.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH less than 7 indicates an acidic solution, while a pH greater than 7 indicates a basic solution. The pH is calculated using the formula pH = -log[H+], where [H+] is the concentration of hydrogen ions in the solution.

Strong Acids

Strong acids, such as HCl and HClO4, completely dissociate in water, meaning that they release all their hydrogen ions into the solution. This complete dissociation simplifies the calculation of pH, as the concentration of the acid directly corresponds to the concentration of hydrogen ions in the solution.

Dilution and Volume Addition

When mixing solutions, the total volume and concentration of the resulting solution must be calculated based on the principle of dilution. The total moles of acid from each solution are combined, and the final concentration is determined by dividing the total moles by the total volume of the mixed solution. This is crucial for accurately calculating the resulting pH.