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Edexcel A-Level Chemistry A2 14.10 Define the Ionic Product of Water Kw Questions

For pure water, set [H+] equal to [OH-], use the given Kw to estimate pH and explain the lower pH through endothermic water dissociation.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
A2

Exam points

  • Use Kw = [H+][OH-] with [H+] = [OH-] to estimate the pH of pure water.
  • Explain that higher temperature increases [H+] because water dissociation is endothermic.
  • State that pure water remains neutral when [H+] and [OH-] are still equal.

Edexcel A-Level Chemistry A2 14.10 Define the Ionic Product of Water Kw Questions question 1

[Maximum number: 1]

At 50°C, the ionic product of water, Kw, is 5.5 × 10^-14 mol^2 dm^-6.
At this temperature, water is

A

neutral with a pH of 7.0

B

neutral with a pH of 6.6

C

acidic with a pH of 6.6

D

alkaline with a pH of 7.4

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