Acid/Base and Redox Reactions Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 1/2

Acid/Base and Redox Reactions

Copyright © 2008 Pearson Prentice Hall, Inc. Chapter 1/2


Acids, Bases, and Neutralization Reactions

H3O1+(aq) + Cl1-(aq)HCl(aq) + H2O(aq)

Acid (Arrhenius): A substance that dissociates in water to produce hydrogen ions, H1+:

H1+(aq) + A1-(aq)HA(aq)

In water, acids produce hydronium ions, H3O1+:

H1+(aq) + Cl1-(aq)HCl(aq)



Ammonia, commonly called “ammonium hydroxide” is a base:

M1+(aq) + OH1-(aq)MOH(aq)

Na1+(aq) + OH1-(aq)NaOH(aq)

NH41+(aq) + OH1-(aq)NH3(aq) + H2O(aq)

Base (Arrhenius): A substance that dissociates in water to produce hydroxide ions, OH1-:



Weak acids and weak bases are weak electrolytes.

Strong acids and strong bases are strong electrolytes.



MA + H2OHA + MOH

These acid-base neutralization reactions are double-replacement reactions just like the precipitation reactions:

or

MA + HOHHA + MOH

WaterAcid Base Salt


Write the chemical formulas of the products (use proper ionic rules for the salt).

1.


Write the molecular, ionic, and net ionic equations for the reaction of aqueous HBr and aqueous Ba(OH)2.

H2OHBr(aq) + Ba(OH)2(aq) + BaBr2

SaltAcid Base Water


Molecular Equation: Balance the equation and predict the solubility of the salt in the products.

2.



2H2O(l) + BaBr2(aq)2HBr(aq) + Ba(OH)2(aq)

Use the solubility rules.


Ionic Equation: Dissociate a strong acid and the soluble ionic compounds.

3.



2H2O(l) + Ba2+(aq) + 2Br1-(aq)

2H1+(aq) + 2Br1-(aq) + Ba2+(aq) + 2OH1-(aq)

BaBr2(aq)

2HBr(aq) Ba(OH)2(aq)


2H2O(l) + Ba2+(aq) + 2Br1-(aq)



Net Ionic Equation: Eliminate the spectator ions from the ionic equation.

4.

2H1+(aq) + 2Br1-(aq) + Ba2+(aq) + 2OH1-(aq)

or

H2O(l)H1+(aq) + OH1-(aq)

2H2O(l)2H1+(aq) + 2OH1-(aq)



Write the molecular, ionic, and net ionic equations for the reaction of aqueous NaOH and aqueous HF.

Write the chemical formulas of the products (use proper ionic rules for the salt).

1.

SaltAcid Base Water

H2OHF(aq) + NaOH(aq) + NaF




Molecular Equation: Balance the equation and predict the solubility of the salt in the products.

2.

H2O(l) + NaF(aq)HF(aq) + NaOH(aq)

Use the solubility rules.




Ionic Equation: Dissociate a strong acid and the soluble ionic compounds.

3.

H2O(l) + Na1+(aq) + F1-(aq)HF(aq) + Na1+(aq) + OH1-(aq)

NaF(aq)

NaOH(aq)




Net Ionic Equation: Eliminate the spectator ions from the ionic equation.

4.

H2O(l) + Na1+(aq) + F1-(aq)HF(aq) + Na1+(aq) + OH1-(aq)

H2O(l) + F1-(aq)HF(aq) + OH1-(aq)


Oxidation-Reduction (Redox) Reactions

2Fe2O3(s)4Fe(s) + 3O2(g)Rusting of iron:an oxidation of Fe

4Fe(s) + 3CO2(g)2Fe2O3(s) + 3C(s)Manufacture of iron: a reduction of Fe

Aqueous potassium

permanganate

Magnesiummetal



1. An atom in its elemental state has an oxidation number of 0.

Rules for Assigning Oxidation Numbers

Oxidation Number (State): A value which indicates whether an atom is neutral, electron-rich, or electron-poor.

Na H2 Br2 S Ne

Oxidation number 0Page 118



2. A monatomic ion has an oxidation number identical to its charge.

Na1+

+1

Ca2+

+2

Al3+

+3

Cl1-

-1

O2-

-2



b) Oxygen usually has an oxidation number of -2.

H O1-

-2+1

HH Ca

-1-1 +2

3. An atom in a polyatomic ion or in a molecular compound usually has the same oxidation number it would have if it were a monatomic ion.a) Hydrogen can be either +1 or -1.

OH O

-1+1 -1

HH O

+1+1 -2

H

+1



H Cl

+1 -1

c) Halogens usually have an oxidation number of -1.3.

ClCl O

+1+1 -2



Cr2O72-

-2+1 x

4. The sum of the oxidation numbers is 0 for a neutral compound and is equal to the net charge for a polyatomic ion.

x = +6

2(x) + 7(-2) = -2 (net charge)

H2SO3

x -2

x = +4

2(+1) + x + 3(-2) = 0 (net charge)

H15 – C4

• 4.9 – 4.11, 4.27*, 4.57, 4.59, 4.63*, 4.65*, 4.101*

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Acid/Base and Redox Reactions Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 1/2