Pure water is ionised according to the equation: 2H2O(l) −⇀↽−\ce{ } H3O+(aq) + OH−(aq) Kw = 10-14 and ΔH = + 57.2 kJ mol-1 As the temperature of pure water is increased, its pH would be expected to

Question

Pure water is ionised according to the equation: 2H2O(l) −⇀↽−\ce{ <=> }  H3O+(aq) +  OH−(aq) Kw = 10-14 and ΔH = + 57.2 kJ mol-1 As the temperature of pure water is increased, its pH would be expected to

BlackTom AI · Accepted Answer

The question concerns how the pH of pure water changes with increasing temperature, given the autoionization: 2 H2O ⇌ H3O+ + OH− with Kw = [H3O+][OH−]. The key concept is that the autoionization of water is endothermic (ΔH > 0). For endothermic equilibria, increasing temperature shifts the equilibrium to the right, increasing Kw. In pure water, [H3O+] = [OH−], so pH = −log[H3O+]. If Kw increases, [H3O+] increases as the square root of Kw (since [H3O+] = [OH−] = sqrt(Kw)), which makes pH = −log(sqrt(Kw)) decrease as Kw grows.

To address potential options (even though the option list is not provided here):
- If an option stated that pH increases with temperature, that would be incorrect because increasing Kw raises [H3O+] and thus lowers pH in pure water.
- If an option claimed pH remains unchanged, that would be incorrect because Kw changes with temperature for water, altering [H3O+].
- If an option suggested pH becomes more acidic (i.e., decreases) as temperature rises, that aligns with the thermodynamic reasoning for an endothermic dissolution whose equilibrium constant Kw increases with temperature.

In summary, as temperature increases, Kw increases for pure water due to the endothermic nature of water autoionization, leading to a higher concentration of hydronium ions and a lower pH. The correct behavioral statement is that the pH decreases with increasing temperature, reflecting greater autoionization and higher [H3O+] in pure water.

Pure water is ionised according to the equation: 2H2O(l) −⇀↽−\ce{ <=> } H3O+(aq) + OH−(aq) Kw = 10-14 and ΔH = + 57.2 kJ mol-1 As the temperature of pure water is increased, its pH would be expected toSingle choice

Similar Questions

What is the concentration of hydroxide ions in pure water at 30.0 °C, if Kw at this temperature is 1.47 × 10-14?

Question at position 16 Which statement is false? Which statement is false? Cold water has a lower pH than hot waterKw = [OH—][H+]Water dissociation is endothermicAs T increases, Kw increases Clear my selection

In the colonies of Victoria and New South Wales, when was Gold discovered?[Fill in the blank]

The Torres Strait Islanders belong to the islands north of which state?[Fill in the blank]

In Australia, voting is compulsory in what elections?[Fill in the blank]

Drop the characteristics of the Overlords Dragon onto its bits:[Fill in the blank]

Please match the following to the letters label on the image[Fill in the blank]

More Practical Tools for Students Powered by AI Study Helper

Homework AI Solver

Stylized AI Paper Writer

Plagiarism Checker Assistant

Citation AI Academic Writing Tool

In-Class Translation Assistant

AI Note Generator

AI Quiz Answers

Past Exam Questions from University Test Bank

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler