slide 1 of 26 chemistry 19.5. © copyright pearson prentice hall slide 2 of 26 salts in solution the...

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Chemistry 19.5

© Copyright Pearson Prentice Hall

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Salts in Solution

The chemical processes inside a living cell are very sensitive to pH. Human blood is normally maintained at a pH very close to 7.4. You will learn about chemical processes that ensure that the pH of blood is kept near 7.4.

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Salts in Solution >

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Salt Hydrolysis

Salt Hydrolysis

When is the solution of a salt acidic or basic?

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Salts in Solution > Salt Hydrolysis

In general, salts that produce acidic solutions contain positive ions that release protons to water. Salts that produce basic solutions contain negative ions that attract protons from water.

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In salt hydrolysis, the cations or anions of a dissociated salt remove hydrogen ions from or donate hydrogen ions to water.

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Salts in Solution > Salt Hydrolysis19.5

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To determine whether a salt solution is acidic or basic, remember the following rules:

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Vapors of the strong acid HCl(aq) and the weak base NH3(aq) combine to form the acidic white salt ammonium chloride (NH4Cl).

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Salts in Solution >

NH4Cl pH 5.3

NaCl pH 7

CH3COONa pH 5.3

Salt Hydrolysis

Universal indicator solution has been added to each of these 0.10M aqueous salt solutions.

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Buffers

Buffers

What are the components of a buffer?

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Salts in Solution > Buffers

A buffer is a solution of a weak acid and one of its salts, or a solution of a weak base and one of its salts.

• The pH of a buffer remains relatively constant when small amounts of acid or base are added.

• The buffer capacity is the amount of acid or base that can be added to a buffer solution before a significant change in pH occurs.

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Buffer of Ethanoic Acid and Sodium Ethanoate

• Adding H+ produces additional ethanoic acid.

• Adding OH- produces additional ethanoate ions.

• The pH changes very little.

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Salts in Solution > Buffers19.5


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Animation 26

Discover the chemistry behind buffer action.

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Salts in Solution > Buffers19.5


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Conceptual Problem 19.2


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Practice Problems for Conceptual Problem 19.2

Problem Solving 19.39 Solve Problem 39 with the help of an interactive guided tutorial.


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Section Quiz

-or-Continue to: Launch:

Assess students’ understanding of the concepts in Section

19.5 Section Quiz.

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1. Which of the following reactions would most likely yield a basic salt solution?

a. strong acid + weak base

b. weak acid + weak base

c. strong acid + strong base

d. weak acid + strong base

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19.5 Section Quiz.

2. Choose the correct words for the spaces. A buffer can be a solution of a _________ and its _________.

a. weak acid, salt

b. strong acid, salt

c. weak acid, conjugate base

d. weak base, conjugate acid


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3. Which of the following equations represents the reaction when a high pH substance is added to a dihydrogen phosphate ion-hydrogen phosphate ion buffer system?

a. H2PO4¯ + OH¯ HPO42¯ + H2O

b. HPO42¯ + OH¯ PO4

3¯ + H2O

c. H2PO4¯ + H+ H3PO4

d. HPO42¯ + H+ H2PO4¯

19.5 Section Quiz.


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Salts in Solution > Concept Map

Concept Map 19

Create your Concept Map using the computer.

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