Final answer:
The higher the pH, the lower the concentration of hydronium (H₃O⁺) ions. Acidic solutions have more hydronium ions and a lower pH, while basic solutions have fewer hydronium ions and a higher pH.
Step-by-step explanation:
The higher the pH, the lower the concentration of H₃O⁺ ions. pH is a scale used to specify the acidity or basicity of an aqueous solution. Acidic solutions have a higher concentration of hydronium ions and a pH value less than 7. As the concentration of hydronium ions increases, the pH decreases, indicating a more acidic solution. Basic solutions, in contrast, have a lower concentration of hydronium ions and a pH value greater than 7.
Hydrochloric acid (HCl) is an example of a strong acid that completely dissociates into H⁺, which is the hydronium ion when it is in water. The more readily an acid donates H⁺, the stronger it is, and consequently, the lower its pH will be. Therefore, the pH scale is inversely related to the concentration of hydronium ions in a solution.