Aqueous Solutions
How do we know ions are present
in aqueous solutions?
The solutions conduct
electricity!
They are called
ELECTROLYTES
Strong Acids and Strong Bases
are strong electrolytes.
They dissociate completely (or
nearly so) into ions.
Aqueous
Solutions
Acetic acid ionizes only to a
small extent, so it is a weak
electrolyte.
CH3CO2H(aq) <--->
CH3CO2-(aq) + H+(aq)
Most of the acid in solution exists
as the UN-IONIZED MOLECULE.
The Double Arrow is used to
indicate that the reaction DOES
NOT RUN COMPLETELY TO
PRODUCTS.
Weak acids and weak
bases are weak
electrolytes.
ACIDS
Acids ---> H+ in water
HCl(aq)
---> H+(aq) + Cl-(aq)
Arrhenius definition of an acid: Any substance
that produces hydrogen ions in water
HCl is a
strong
acid
Other strong acids
include:
HI, HBr, HNO3, HCl,
H2SO4, HClO4, HClO3
ACIDS
Nonmetal oxides can produce acids
CO2(aq) + H2O ---> H2CO3(aq)
SO3(aq) + H2O ---> H2SO4(aq)
and can come from burning coal and
oil.
*You need to know this reaction!
What are the properties of
acids and bases?

ACIDS:

BASES:

pH – Low <7

pH – High, >7

Taste – Sour

Taste - Bitter

Litmus color – Red

Litmus color - Blue

Feel – Slippery

Phenolphthalein color
- Colorless
Litmus is an extract
from lichens that is
used as a pH indicator

Phenolphthalein color Pink
BASES
Base ---> OH- in water
NaOH(aq)
---> Na+(aq) + OH-(aq)
Arrhenius definition of a base: Any substance
that produces hydroxide ions in water
NaOH is a
strong
base
Other strong bases
include:
LiOH, KOH, NaOH,
RbOH, Cs(OH)2,
Ba(OH)2, Sr(OH)2
Ammonia, NH3
An Important Weak Base
Even though ammonia does not
have hydroxide ion in its formula, it
is a base because it interacts with
water to produce hydroxide ions!
Because it is a WEAK base, ammoniua
does NOT produce MANY OH- in water.
The Double Arrows indicate that this
reaction does NOT run completely to
products.
BASES
Metal oxides can produce bases
in water:
CaO(s) + H2O --> Ca(OH)2(aq)
*You need to know this reaction.
CaO in water. Indicator
shows solution is basic.
Acid-Base Reactions

The “driving force” is the
formation of water.
NaOH(aq) + HCl(aq)  NaCl(aq) + H2O(liq)




Net ionic equation
OH-(aq) + H+(aq)---> H2O(liq)
This applies to ALL reactions
of STRONG acids and bases.
WATER will NOT split back up
into IONS*
What are the SPECTATOR
IONS in this reaction??
A DRIVING FORCE of a
reaction is a PRODUCT the
does NOT ALLOW the
reaction to run back toward
REACTANTS. It FORCES
the reaction FORWARD to
PRODUCTS!
Acid-Base Reactions


Acid-Base reactions are sometimes called
NEUTRALIZATION Reactions because the
solution is neither acidic nor basic at the end.
The other product of the Acid-Base reaction is
a SALT and water.
HCl + NaOH ---> NaCl + H2O
This is one way to make compounds!
Gas-Forming Reactions
There are four important gas-forming reactions to learn. Make a list of
gases formed in these reactions.
The formation of a GAS is the DRIVING FORCE in these reactions!
Once the GASES leave the reaction vessel, the reaction CANNOT
turn back into REACTANTS. Gas formation drives the reaction to
PRODUCTS.