Question

Calculate the concentration of hydroxide ion for blood with a hydronium ion concentration of 4.2 x 10⁻⁸m

a) 2.4 x 10⁻⁷ M

b) 4.2 x 10⁻²² M

c) 4.2 x 10⁺⁶ M

d) 2.4 x 10⁻⁶ M

Answer 1

To determine the concentration of hydroxide ions in blood, divide the ion product of water (1.0 × 10^-14 M^2) by the given concentration of hydronium ions (4.2 × 10^-8 M) to get a concentration of hydroxide ions of 2.4 × 10^-7 M.

Step-by-step explanation:

To calculate the concentration of hydroxide ion (OH-) in blood with a given hydronium ion (H3O+) concentration, we utilize the ion product of water at 25 °C, which is 1.0 × 10-14 M2. This product is constant and is the result of multiplying the concentration of hydronium ions by the concentration of hydroxide ions in aqueous solution.

The formula to find the hydroxide ion concentration is given by: [OH-] = KW / [H3O+], where KW is the ion product of water (1.0 × 10-14 M2).

Given the concentration of hydronium ions is 4.2 × 10-8 M, the calculation for the hydroxide ion concentration is as follows:

[OH-] = (1.0 × 10-14) / (4.2 × 10-8)

[OH-] = 2.38 × 10-7 M (rounded to two significant figures).

Therefore, the concentration of hydroxide ions in the blood is 2.4 × 10-7 M.