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Hydrogen Ions and Acidity

To test a diagnosis of diabetic coma, a doctor orders several tests, including the acidity of the patient’s blood. Results from this test will be expressed in units of pH. You will learn how the pH scale is used to indicate the acidity of a solution and why the pH scale is used.

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Hydrogen Ions and Acidity >

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The pH Concept

The pH Concept

How is the hydrogen-ion concentration used to classify a solution as neutral, acidic, or basic?

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>Hydrogen Ions and Acidity The pH Concept

A solution in which [H+] is greater than 1 10–7 M has a pH less than 7.0 and is acidic.

The pH of pure water or a neutral aqueous solution is 7.0.

A solution with a pH greater than 7 is basic and has a [H+] of less than 1 10–7 M.

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>Hydrogen Ions and Acidity19.2 The pH Concept

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>Hydrogen Ions and Acidity The pH Concept19.2

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>Hydrogen Ions and Acidity The pH Concept

pH and Significant Figures

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Hydrogen Ions and Acidity >

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Measuring pH

Measuring pH

What is the most important characteristic of an acid-base indicator?

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Hydrogen Ions and Acidity >

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Measuring pH

An indicator is a valuable tool for measuring pH because its acid form and base form have different colors in solution.

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>Hydrogen Ions and Acidity Measuring pH

Phenolphthalein changes from colorless to pink at pH 7–9.

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>Hydrogen Ions and Acidity Measuring pH

Universal Indicators

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>Hydrogen Ions and Acidity Measuring pH

pH Meters

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>Hydrogen Ions and Acidity Measuring pH

Sample Questions:

A solution in which the hydroxide ion concentration is 1 x 10 -5 is

a. Acidic

b. Basic

c. Neutral

d. None of the above

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>Hydrogen Ions and Acidity Measuring pH

Sample Questions:

Which of these solutions is most basic?

a. [H+] = 1 x 10 -11

b. [OH-] = 1 x 10-4

c. [H+] = 1 x 10 -2

d. [OH-] = 1 x 10 -13

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