At 0 °C, the density of liquid water is 0.9998 g/mL and the value of Kw is 1.14 * 10-15. What fraction of the molecules in liquid water are dissociated at 0 °C? What is the percent dissociation at 0 °C? What is the pH of a neutral solution at 0 °C?

Water undergoes a self-ionization process where a small fraction of water molecules dissociate into hydrogen ions (H⁺) and hydroxide ions (OH⁻). This equilibrium is represented by the equation: 2 H₂O ⇌ H₃O⁺ + OH⁻. The equilibrium constant for this reaction at a given temperature is denoted as Kw, which reflects the product of the concentrations of the ions produced.

Kw, the ion product of water, is defined as the product of the concentrations of H⁺ and OH⁻ ions in water. At 0 °C, Kw is given as 1.14 × 10⁻¹⁵. The pH of a solution is calculated using the formula pH = -log[H⁺]. In pure water, the concentrations of H⁺ and OH⁻ are equal, allowing us to determine the pH based on the value of Kw.

Percent dissociation refers to the fraction of the total number of molecules that have dissociated into ions. It can be calculated using the formula: (number of dissociated molecules / total number of molecules) × 100%. To find this value for water at 0 °C, one must first determine the concentration of dissociated ions from Kw and relate it to the total concentration of water.