Chapter 4 Aqueous Reactions
Solutions: ___________________________ of two or more pure substances.
The ______________ is present in greatest abundance.
All other substances are _________________.
Aqueous Solutions =
Water is a good solvent because ______________________________.
The oxygen atoms have ____________________________
The hydrogen atoms have __________________________
The angle is 105ºC.
Dissociation =
When an ionic substance dissolves in water, the solvent pulls the individual ions from the crystal and ionizes them. This process is called dissociation or ionization.
Electrolytes
Nonelectrolytes
Strong
Electrolyte
Weak
Electrolyte
Strong Electrolytes Are…
Weak Electrolytes Are…

Types of Reactions
PRECIPITATION REACTIONS -
_____________________________________________________________.
A solid that forms from mixed solutions is a
If you’re not a part of the solution, your part of the precipitate!
When one mixes ions that form compounds that are insoluble (as could be predicted by the solubility guidelines), a precipitate is formed.
We can predict the products
Double Replacement Reactions
AgNO
3
(aq) + KCl(aq) 
Zn(NO
3
)
2
(aq) + BaCr
2
O
7
(aq) 
CdCl
2
(aq) + Na
2
S(aq) 
The molecular equation lists the reactants and products in their molecular form.
AgNO
3
(aq) + KCl (aq)  AgCl (s) + KNO
3
(aq)
In the ionic equation all strong electrolytes (strong acids, strong bases, and soluble ionic salts) are dissociated into their ions.
To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right.

The only things left in the equation are those things that change (i.e., react) during the course of the reaction.
Those things that didn’t change (and were deleted from the net ionic equation) are called spectator ions.
Molecular Equation- written as whole formulas, not the ions.
K
2
CrO
4
(aq) + Ba(NO
3
)
2
(aq) 
Complete Ionic equation shows dissolved electrolytes as the ions.
Spectator ions are those that don’t react.
Net Ionic equations show only those ions that react, not the spectator ions
Writing Net Ionic Equations
1.
2.
3.
4.

Write the three types of equations for the reactions when these solutions are mixed.
An aqueous solution of iron (III) sulfate reacts with an aqueous solution of potassium sulfide
An aqueous solution of lead (II) nitrate reacts with an aqueous solutions of sulfuric acid

Acids:
 Substances that ___________________________when dissolved in water
(Arrhenius).
 ______________________(Brønsted–Lowry).
There are only seven strong acids:
Bases:
 Substances that ___________________________when dissolved in water
(Arrhenius).
 ______________________(Brønsted–Lowry)
The strong bases are the soluble salts of hydroxide ion:
Alkali metals
Calcium
Strontium
Barium
Acid-Base Reactions In an acid-base reaction,

NEUTRALIZATION REACTIONS
Generally, when solutions of an acid and a base are combined, the product are
____________ and _______________
When a strong acid reacts with a strong base, the net ionic equation is…
GAS-FORMING REACTIONS
These double replacement reactions do not give the product expected.
The expected product (H
2
CO
3
) decomposes to give a gaseous product (CO
2
or SO
2
).
This reaction gives the predicted product, but you had better carry it out in the hood, or you will be very unpopular!
Just as in the previous examples, a gas is formed as a product of this reaction:

OXIDATION-REDUCTION REACTIONS also called Redox Reactions
Involves the transfer of _____________________
We need a way of keeping track of electrons being transferred.
( )
An ___________________ occurs when an atom or ion __________________.
A ____________________occurs when an atom or ion __________________.
One cannot occur without the other!
Oxidation
Reduction
The substance that is oxidized is called the reducing agent.
The substance that is reduced is called the oxidizing agent.

Redox Reactions



Oxidation Numbers / Oxidation States (see oxidation numbers handout)
Assign the oxidation states to each element in the following.
CO
2
NO
3
H
2
SO
4
Fe
2
O
3
FeO
Assign oxidation numbers and identify the atom being oxidized, reduced, the oxidizing agent, and the reducing agent:
A piece of calcium is placed in hydrochloric acid.
A piece of calcium is exposed to air.