Question

The hydroxide ion concentration in household ammonia is 3.2 × 10⁻³ M at 25 °C. What is the concentration of hydronium ions in the solution?

a) 3.1 × 10⁻¹¹ M
b) 3.1 × 10⁻⁴ M
c) 3.1 × 10⁻⁷ M
d) 3.1 × 10⁻¹⁴ M

Answer 1

To determine the hydronium ion concentration in household ammonia with a given hydroxide ion concentration, we use the ion product of water at 25 °C, which is equal to 1.0 × 10−14 M². Dividing this constant by the hydroxide ion concentration gives us the hydronium ion concentration of 3.1 × 10−11 M.The correct answer is option A.

Step-by-step explanation:

The question asks us to find the concentration of hydronium ions in a solution of household ammonia which has a known hydroxide ion concentration at 25 °C. To solve for the hydronium ion concentration, we use the relationship between hydronium and hydroxide concentrations in water, which is given by the ion product of water: Kw = [H3O+][OH−], where Kw is 1.0 × 10−14 M2 at 25 °C.

We have the hydroxide ion concentration ([OH−]) which is 3.2 × 10−3 M, so we can find the hydronium ion concentration ([H3O+]) by rearranging the equation to [H3O+] = Kw / [OH−].

Substitute the given values into the equation:

[H3O+] = (1.0 × 10−14 M2) / (3.2 × 10−3 M)
= 3.125 × 10−11 M

Therefore, the correct answer for the concentration of hydronium ions in the solution is 3.1 × 10−11 M, which corresponds to option a) 3.1 × 10−11 M.