1. Chapter 4 Reactions in Aqueous Solution
Chemistry: McMurry and Fay, 6th Edition
Chapter 4: Reactions in Aqueous Solution
11/23/2018 6:54:02 AM
Chapter 4 Reactions in Aqueous Solution
© 2012 Pearson Education, Inc.
Copyright © 2011 Pearson Prentice Hall, Inc.

2. Naming Chemical Compounds
Chapter 2: Atoms, Molecules, and Ions
11/23/2018
Naming Chemical Compounds
Binary Acids
HCl hydrochloric acid
HBr hydrobromic acid
HF hydrofluoric acid
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

3. Naming Chemical Compounds
Chapter 2: Atoms, Molecules, and Ions
Naming Chemical Compounds
11/23/2018
Oxoacids do not begin with “hydro.”
Hydrochloric acid: HCl
Chloric acid: HClO3
“ous”
“ite”
“ic”
“ate”
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

4. Examples
Name the following acids HI
HCN
HNO3
H2PO4

5. Acids, Bases, and Neutralization Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Acids, Bases, and Neutralization Reactions
Acid (Arrhenius): A substance that dissociates in water to produce hydrogen ions, H1+:
H1+(aq) + A1-(aq)
HA(aq)
H1+(aq) + Cl1-(aq)
HCl(aq)
In water, acids produce hydronium ions, H3O1+:
H3O1+(aq) + Cl1-(aq)
HCl(aq) + H2O(aq)
“HA” is a generic chemical formula for an acid.
Hydrogen ions do not exist in water. They are attached to one or more water molecules (often in clusters). For convenience, we’ll write it as hydrogen ion instead of hydronium ion until a later chapter when a deeper look at acids and bases is undertaken.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

6. Acids, Bases, and Neutralization Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Acids, Bases, and Neutralization Reactions
Base (Arrhenius): A substance that dissociates in water to produce hydroxide ions, OH1-:
M1+(aq) + OH1-(aq)
MOH(aq)
Na1+(aq) + OH1-(aq)
NaOH(aq)
Ammonia, commonly called “ammonium hydroxide” is a base:
“M” is shorthand for a metal cation.
It’s really not proper to call “aqueous ammonia” “ammonium hydroxide” even though it’s still commonly labeled as such (ordering chemicals, etc.).
NH41+(aq) + OH1-(aq)
NH3(aq) + H2O(aq)
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

7. Acids, Bases, and Neutralization Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Acids, Bases, and Neutralization Reactions
Strong acids and strong bases are strong electrolytes.
Weak acids and weak bases are weak electrolytes.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

8. Acids, Bases, and Neutralization Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Acids, Bases, and Neutralization Reactions
These acid-base neutralization reactions are double-replacement reactions just like the precipitation reactions:
MA HOH
HA MOH or
Recall the original definition of an acid-base neutralization written earlier.
While it looks goofy to write water as HOH, it can help students remember where the pieces came from: H (acid) and OH (base). It’s also easier to balance.
MA H2O
HA MOH
Acid
Base
Salt
Water
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

9. Acids, Bases, and Neutralization Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Acids, Bases, and Neutralization Reactions
Write the molecular, ionic, and net ionic equations for the reaction of aqueous HBr and aqueous Ba(OH)2. 1.
Write the chemical formulas of the products (use proper ionic rules for the salt).
HBr(aq) +
Ba(OH)2(aq)
H2O +
BaBr2
Acid
Base
Water
Salt
The order the products are written in is irrelevant.
The products will be water and a salt.
The salt is written using the rules for naming ionic compounds as previously used.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

10. Acids, Bases, and Neutralization Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Acids, Bases, and Neutralization Reactions
Write the molecular, ionic, and net ionic equations for the reaction of aqueous NaOH and aqueous HF. 1.
Write the chemical formulas of the products (use proper ionic rules for the salt).
HF(aq) + NaOH(aq)
H2O +
NaF
Acid
Base
Water
Salt
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

11. Examples
Predict the product and write a molecular equation, ionic equation and net ionic equation for the following reactions
K2CO3(aq) + NiCl2(aq) 
H2NO3(aq) + LiOH(aq) 
HCN(aq) + Mg(OH)2

12. Oxidation-Reduction (Redox) Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Oxidation-Reduction (Redox) Reactions
Rusting of iron:
an oxidation of Fe
2Fe2O3(s)
4Fe(s) + 3O2(g)
Manufacture of iron: a reduction of Fe
4Fe(s) + 3CO2(g)
2Fe2O3(s) + 3C(s)
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

13. Oxidation-Reduction (Redox) Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Oxidation-Reduction (Redox) Reactions
Oxidation Number (State): A value which indicates whether an atom is neutral, electron-rich, or electron-poor.
Rules for Assigning Oxidation Numbers
An atom in its elemental state has an oxidation number of 0. Na H2
Br2 S Ne
Oxidation number 0
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

14. Oxidation-Reduction (Redox) Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Oxidation-Reduction (Redox) Reactions
A monatomic ion has an oxidation number identical to its charge.
Na1+ +1
Ca2+ +2
Al3+ +3
Cl1- -1
O2- -2
This is why charges are supposed to be written as “1-”. The corresponding oxidation number is written “-1”.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

15. Oxidation-Reduction (Redox) Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Oxidation-Reduction (Redox) Reactions
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.
Hydrogen can be either +1 or -1. H O 1- H Ca +1 -2 -1 +2 -1
Oxygen usually has an oxidation number of -2. H O H O O H
H bonded to a nonmetal has an oxidation number of +1.
H bonded to a metal has an oxidation number of -1.
In peroxides, O22-, oxygen has an oxidation number of -1. +1 -2 +1 +1 -1 -1 +1
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

16. Oxidation-Reduction (Redox) Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Oxidation-Reduction (Redox) Reactions
Halogens usually have an oxidation number of -1. 3. H Cl Cl O +1 -1 +1 -2 +1
A major exception is when the halogen is bonded to oxygen.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

17. Oxidation-Reduction (Redox) Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Oxidation-Reduction (Redox) Reactions
The sum of the oxidation numbers is 0 for a neutral compound and is equal to the net charge for a polyatomic ion.
2(+1) + x + 3(-2) = 0 (net charge)
H2SO3
x = +4 +1 x -2
Cr2O72-
2(x) + 7(-2) = -2 (net charge)
x = +6 x -2
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

18. Example
Determine the oxidation number for each atom in the following compounds/molecules
SrBr2
CCl4
SO42-

19. Identifying Redox Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Identifying Redox Reactions
Oxidizing Agent
Causes oxidation
Gains one or more electrons
Undergoes reduction
Oxidation number of atom decreases
Reducing Agent
Causes reduction
Loses one or more electrons
Undergoes oxidation
Oxidation number of atom increases
An “agent” causes something to happen.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

20. Identifying Redox Reactions
Chapter 4: Reactions in Aqueous Solution
11/23/2018
Identifying Redox Reactions
Oxidizing Agent
2Fe2
3O2(g) +
4Fe(s) O3
(s) +3
oxidation
reduction -2
Reducing Agent
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

21. Example Identify each of the following as
1) oxidation or 2) reduction.
__A. Sn(s) Sn4+(aq) e−
__B. Fe3+(aq) e− Fe2+(aq)
__C. Cl2(g) e− Cl-(aq)

22. Writing Oxidation and Reduction Reactions
Write the separate half oxidation and reduction reactions for the following equation.
2Cs(s) F2(g) CsF(s)
3 Na(l) + AlCl3(l) 3  NaCl(l) + Al(l)

23. The Activity Series of the Elements
Chapter 4: Reactions in Aqueous Solution
11/23/2018
The Activity Series of the Elements
Cu2+(aq) + 2Ag(s)
Cu(s) + 2Ag1+(g)
Which one of these reactions will occur?
2Ag1+(aq) + Cu(s)
2Ag(s) + Cu2+(g)
These are net ionic equations. The spectator ions (nitrate, for one example) are not involved in the main reaction.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

24. The Activity Series of the Elements
Chemistry: McMurry and Fay, 6th Edition
Chapter 4: Reactions in Aqueous Solution
11/23/2018 6:54:02 AM
The Activity Series of the Elements
Fe2+(aq) + Cu(s)
Fe(s) + Cu2+(aq)
This is a net ionic equation. The spectator ions (nitrate, for one example) are not involved in the main reaction.
© 2012 Pearson Education, Inc.
Copyright © 2011 Pearson Prentice Hall, Inc.

25. The Activity Series of the Elements
Chemistry: McMurry and Fay, 6th Edition
Chapter 4: Reactions in Aqueous Solution
11/23/2018 6:54:02 AM
The Activity Series of the Elements
Elements that are higher up in the table are more likely to be oxidized.
Thus, any element higher in the activity series will reduce the ion of any element lower in the activity series.
© 2012 Pearson Education, Inc.
Copyright © 2011 Pearson Prentice Hall, Inc.

26. The Activity Series of the Elements
Chapter 4: Reactions in Aqueous Solution
11/23/2018
The Activity Series of the Elements
Cu2+(aq) + 2Ag(s)
Cu(s) + 2Ag1+(g)
Which one of these reactions will occur?
2Ag1+(aq) + Cu(s)
2Ag(s) + Cu2+(g)
This is a nice one to do as a demonstration. Place a coil of copper wire in a solution of silver nitrate at the beginning of lecture or lab and show it to the students. Show it again at the end of the period.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

27. Example
Predict whether the following redox reactions will occurred or not. If so, predict the products
Zn(s) + FeCl2(aq) 
Ni(s) + Mg(NO3)2(aq) 

28. Chapter 4: Reactions in Aqueous Solution
Redox Titrations
11/23/2018
Titration: A procedure for determining the concentration of a solution by allowing a carefully measured volume to react with a solution of another substance (the standard solution) whose concentration is known.
5H2C2O4(aq) + 2MnO41-(aq) + 6H1+(aq)
10CO2(g) + 2Mn2+(aq) + 8H2O(l)
If the unknown concentration is the potassium permanganate solution, MnO41-, it can be slowly added to a known amount of oxalic acid, H2C2O4, until a faint purple color persists.
The net ionic equation is shown.
Potassium permanganate is dark purple. As it’s added to a solution of oxalic acid, the permanganate reacts to form Mn2+ and remains colorless (dilute solutions of Mn2+ are colored but it can be difficult to see). When a slight excess of permanganate is added, the solution turns faint purple.
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

29. Chapter 4: Reactions in Aqueous Solution
11/23/2018
Redox Titrations
A solution is prepared with g of oxalic acid, H2C2O mL of an unknown solution of potassium permanganate are needed to titrate the solution. What is the concentration of the potassium permanganate solution?
5H2C2O4(aq) + 2MnO41-(aq) + 6H1+(aq)
10CO2(g) + 2Mn2+(aq) + 8H2O(l)
Copyright © 2008 Pearson Prentice Hall, Inc.
Copyright © 2008 Pearson Prentice Hall, Inc.

30. Calculation Set up Mass of H2C2O4 Moles of H2C2O4 Moles of KMnO4
Molarity of
KMnO4
Mole Ratio
Molar Mass of H2C2O4
Molarity of KMnO4

31. Example
A M standard solution of potassium permanganate was titrated against 25.00mL of an iron (II) sulfate solution. The equivalence point, as indicated by a faint pink color, was reached when 15.50mL of potassium permanganate solution had been added. Calculate the concentration of the iron (II) sulfate solution