What does the dissociation constant of water (Kw) equal?

What does the dissociation constant of water (Kw) equal?

• A. 1.0 x 10^-7
• B. 1.0 x 10^-10
• C. 1.0 x 10^-14
• D. 1.0 x 10^-16

Answer: (C)

The dissociation constant of water, denoted as Kw, is a fundamental concept in chemistry, particularly in acid-base chemistry. It represents the equilibrium constant for the dissociation of water into hydrogen ions (H⁺) and hydroxide ions (OH⁻). The balanced equation for this dissociation can be represented as: \[ H_2O \rightleftharpoons H^+ + OH^- \] At 25°C (298 K), the concentration of hydrogen ions and hydroxide ions in pure water is both 1.0 x 10^-7 mol/L. Therefore, Kw can be expressed as the product of these concentrations: \[ Kw = [H^+][OH^-] = (1.0 \times 10^{-7})(1.0 \times 10^{-7}) = 1.0 \times 10^{-14} \] This means that the value of Kw at 25°C is 1.0 x 10^-14. This constant is crucial for understanding pH, as it helps to determine the concentration of H⁺ ions and relates to the acidity or basicity of a solution. The other values presented do not correspond to the dissociation constant of

The dissociation constant of water, denoted as Kw, is a fundamental concept in chemistry, particularly in acid-base chemistry. It represents the equilibrium constant for the dissociation of water into hydrogen ions (H⁺) and hydroxide ions (OH⁻). The balanced equation for this dissociation can be represented as:

[

H_2O \rightleftharpoons H^+ + OH^-

]

At 25°C (298 K), the concentration of hydrogen ions and hydroxide ions in pure water is both 1.0 x 10^-7 mol/L. Therefore, Kw can be expressed as the product of these concentrations:

[

Kw = [H^+][OH^-] = (1.0 \times 10^{-7})(1.0 \times 10^{-7}) = 1.0 \times 10^{-14}

]

This means that the value of Kw at 25°C is 1.0 x 10^-14. This constant is crucial for understanding pH, as it helps to determine the concentration of H⁺ ions and relates to the acidity or basicity of a solution.

The other values presented do not correspond to the dissociation constant of