Calculate [H⁺] for each of the following solutions, and indicate whether the solution is acidic, basic, or neutral: (a) [OH^-] = 0.00045 M (b) [OH^-] = 8.8 × 10^-9 M (c) a solution in which [OH^-] is 100 times greater than [H⁺].

Verified step by step guidance

1. Identify the given concentration: \([OH^-] = 8.8 \times 10^{-9} \text{ M}\).
2. Use the water dissociation constant \(K_w = 1.0 \times 10^{-14}\) to find \([H^+]\) using the formula \([H^+] = \frac{K_w}{[OH^-]}\).
3. Substitute the given \([OH^-]\) value into the formula: \([H^+] = \frac{1.0 \times 10^{-14}}{8.8 \times 10^{-9}}\).
4. Calculate the \([H^+]\) concentration from the above expression.
5. Determine the nature of the solution: if \([H^+] > 1.0 \times 10^{-7}\) M, it's acidic; if \([H^+] < 1.0 \times 10^{-7}\) M, it's basic; if \([H^+] = 1.0 \times 10^{-7}\) M, it's neutral.

Key Concepts

pH and pOH

pH is a measure of the hydrogen ion concentration in a solution, indicating its acidity or basicity. The pH scale ranges from 0 to 14, with values below 7 being acidic, 7 being neutral, and above 7 being basic. pOH, on the other hand, measures the hydroxide ion concentration and is related to pH through the equation pH + pOH = 14.

Ion Product of Water (Kw)

The ion product of water (Kw) is the equilibrium constant for the self-ionization of water, defined as Kw = [H+][OH-] = 1.0 x 10^-14 at 25°C. This relationship allows us to calculate the concentration of hydrogen ions from the hydroxide ion concentration and vice versa, which is essential for determining the pH of a solution.

Acidic, Basic, and Neutral Solutions

A solution is classified as acidic if its pH is less than 7, basic if its pH is greater than 7, and neutral if its pH equals 7. The classification is determined by the relative concentrations of H+ and OH- ions in the solution, which can be calculated using the pH and pOH values derived from the concentrations of these ions.