Final answer:
The true statement for a 0.10M solution of HCl is that [H3O+]eq is equal to 0.10M since HCl is a strong acid and dissociates completely in aqueous solution, yielding a hydronium ion concentration equal to its initial molarity.
Step-by-step explanation:
The correct statement for a 0.10M solution of HCl is that the hydronium ion concentration, denoted as [H3O+]eq, is equal to 0.10M. This is because hydrochloric acid (HCl) is a strong acid, which means it dissociates completely in aqueous solutions. When HCl dissociates, it releases one hydronium ion (H3O+) for each molecule of acid, resulting in a 1:1 stoichiometry between HCl and H3O+. Therefore, the initial 0.10M concentration of HCl will result in an equimolar concentration of hydronium ions.
The pH of the solution can be calculated using the formula pH = -log[H3O+], which for a 0.10M solution of HCl results in a pH of 1. This matches with the properties of a strong acid solution indicating high acidity. Furthermore, since the product of [H+] and [OH-] in any aqueous solution is always 1.0×10-14, the [OH-] concentration in a 0.10M HCl solution will be very low, indicating an acidic solution.