Determine each of the following for a 0.100 M HBr solution:
b. pH

Verified step by step guidance

1. Step 1: Recognize that HBr is a strong acid, meaning it completely dissociates in water. This implies that the concentration of H⁺ ions ([H⁺]) in the solution is equal to the initial concentration of HBr.
2. Step 2: Write the relationship between the concentration of H⁺ ions and the pH of the solution. The formula is: $\mathrm{pH}=-log\left(H_{+}\right)$
3. Step 3: Substitute the given concentration of HBr (0.100 M) into the formula for [H⁺], since [H⁺] = 0.100 M for a strong acid like HBr.
4. Step 4: Use the logarithmic function to calculate the pH. Specifically, take the negative logarithm (base 10) of the [H⁺] concentration: $\mathrm{pH}=-log\left(0.100\right)$
5. Step 5: Interpret the result. The pH value will indicate the acidity of the solution, with lower values corresponding to higher acidity. Since HBr is a strong acid, the pH should be relatively low.

Key Concepts

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is neutral, while values below 7 indicate acidity and values above 7 indicate alkalinity. The scale is logarithmic, meaning each whole number change represents a tenfold change in hydrogen ion concentration.

Strong Acids

Strong acids, like HBr, completely dissociate in water, releasing all their hydrogen ions (H+). This complete dissociation means that the concentration of the acid directly correlates with the concentration of H+ ions in the solution, making it straightforward to calculate the pH of strong acid solutions.

Calculating pH

To calculate the pH of a solution, the formula pH = -log[H+] is used, where [H+] is the concentration of hydrogen ions. For a 0.100 M HBr solution, since it fully dissociates, the [H+] is also 0.100 M, leading to a pH calculation of -log(0.100), which results in a pH of 1.00.