Question

What is the OH⁻ concentration in 25 x 10⁻¹² M HCI solution?

A. 40 x 10¹² M
B. 40 x 10⁻¹² M
C. 2.5x 10⁻¹¹ M
D. None of these
E. 2.5 x 10⁻³M

Answer 1

The concentration of hydroxide ions in a 25 x 10^-12 M HCl solution is 2.5 x 10^-3 M, calculated using the ion product constant for water (Kw) at 25 °C. Therefore correct option is E

Step-by-step explanation:

The question asks for the concentration of hydroxide ions (OH-) in a solution of HCI, which is a strong acid. The concentration of HCI given is 25 x 10-12 M. In a solution of a strong acid like HCI, it will dissociate completely into hydronium ions (H3O+) and chloride ions (Cl-).

The concentration of hydronium ions will be equal to the concentration of the acid, 25 x 10-12 M.

At 25 °C, the product of hydronium ion concentration and hydroxide ion concentration is constant, known as the ion product constant for water, Kw = 1.0 × 10-14. Using this relationship, we can calculate the hydroxide ion concentration.

[OH-] = Kw / [H3O+]

= 1.0 × 10-14 / 25 x 10-12 M

= 4.0 × 10-3 M

Therefore, the correct answer is E. 2.5 × 10-3 M.