Calculate the pH of each of the following strong acid solutions: (b) 0.225 g of HClO₃ in 2.00 L of solution

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Determine the molar mass of HClO_3 by adding the atomic masses of hydrogen (H), chlorine (Cl), and oxygen (O).

Convert the mass of HClO_3 (0.225 g) to moles using the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).

Calculate the concentration of HClO_3 in the solution by dividing the number of moles by the volume of the solution in liters (2.00 L).

Since HClO_3 is a strong acid, it dissociates completely in water. Therefore, the concentration of HClO_3 is equal to the concentration of H^+ ions.

Calculate the pH of the solution using the formula: \( \text{pH} = -\log[\text{H}^+] \).

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Key Concepts

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

Strong Acids

Strong acids are substances that completely dissociate in water, releasing all of their hydrogen ions (H+) into the solution. This complete ionization means that the concentration of H+ ions in the solution is equal to the concentration of the acid. For example, hydrochloric acid (HCl) and chloric acid (HClO3) are both strong acids, which simplifies the calculation of pH since we can directly use the molarity of the acid to find the pH.

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. To calculate the molarity of HClO3 in the given problem, we first need to convert the mass of HClO3 to moles using its molar mass, and then divide by the volume of the solution in liters. This value is crucial for determining the concentration of H+ ions, which directly affects the pH.

pH Scale

The pH scale is a logarithmic scale used to quantify the acidity or basicity of a solution, with values ranging from 0 to 14. A pH of 7 is considered neutral, while values below 7 indicate acidity and values above 7 indicate basicity. The pH is calculated using the formula pH = -log[H+], where [H+] is the concentration of hydrogen ions in moles per liter. For strong acids, the pH can be directly calculated from the molarity of the acid.