Characterisitcs of Acids:
1. Molecular substances that IONIZE in water.
The overall electronegativity difference is less than 1.8- it’s a non-polar
covalent molecule- but it creates ions in solution.
2. Acids react with active metals to create Hydrogen gas: Active metals include
Na, Mg, Zn, Fe. Copper, Silver, Gold, and Platinum DO NOT react with
acids. This equation (in general) is:
Metal + Acid  Metallic Salt + H2 (g)
3. Acids affect the color of indicators.
4. Acids react with bases to produce a more neutral solution of Water and a
metallic salt.
5. Those acids that are edible have a sour taste- they include Carbonic,
Phophoric, Acetic, and Oxalic acids are present in many foods that have a
characteristic sour taste: Citrus fruits, vinegar, Coke. Another is Salicylic
Acid, which is found in aspirin.
Arrhenuis Acids: A solution that yields an H+ ion (a bare proton) as one of its
components in solutions.
The bare proton is always aqueous- that is, tied up with a molecule of water. In strong
acids, 1 H+ proton = 1 hydronium ion (1H2O for every 1H+ ion). Conversely, in weak
acids, there are generally more water molecules for every H+.
Ionization: Each acid has stable rate of ionization, in which the concentration of the
compounds is compared to the concentration of the ions in solution. The higher the rate
of ionization, the more powerful the acid.
Strong: HCl: nearly 100% ionized.
Nitric (HNO3) Nearly 100%
Sulfuric Acid (H2SO4) around 96% ionized
Weak: Hydrofloric Acid (HF)- About 0.3% ions in soution
Acetic Acid (HC2H3O2)- about 0.001% ions.
Hydrosulfuric Acid- About 0.0000003%ions.
Properties of Bases:
1. Bases are electrolytes; they will conduct electricity in a solution of water.
They dissolve quite readily into the ions that make them up.
2. Bases will cause indicators to turn various colors.
3. Bases neutralize acids, producing a metallic salt plus water.
4. Bases tend to be bitter tasting, and have a very slippery feel.
- Soap in the mouth? Soap is a base mixed with fats or oils.
Arrhenuis Bases:
Contribute a OH- (Hydroxide ion) in solution.
Bases in solution are characterized by the presence of OH- ions tied in solution.
The OH-, unlike the H+, does not attach itself to another molecule UNLESS it has an
extra H+ (to create water- thus explaining why acids and bases react so readily.
Ionization of Bases: Ionize similar to acids, except that Bases tend to be IONIC
compounds. The OH- ion is a molecular (covalent) compound, while the metal attached
will be bonded ionically.
Strong Bases: NaOH (almost 100%)
KOH (again)
Weak Bases: Ammonia compounds: NH4OH, NH3-H2O, etc.—rarely reach
30%.
Salts
Salts are defined as ionic compounds that have ions other than H+ and OH- as
their cation and anion, respectively. When solid, salts will represent a LATTICE: A
regular, repeating shape in which the negative ions of one molecule are surrounded by the
positive ions of other molecules.
They conduct electricity when molten OR in solution; they also tend to have very
high melting points.
Salts are very useful in our daily lives: NaCal, CaCl2, (eating, melting snow, etc.);
NaNO3- preservative; NaHCO3- Sodium Bicarbonate, baking soda; K2CO3, potash,
used to fertilize plants and making gunpowder
Arrhenuis based his theories on Operational definitions, or Observable properties. He
saw that acids are sour, they make certain indicators turn certain colors, etc.
IONIZATION of water.
The uniquie qualites of water are what allow us to live on this planet: one is that
its solid form is less dense than it’s liquid form; another is that it’s polar, allowing for
non-polar organic molecules to form in water quite readily; another is that it ionizes
(dissolves) in itself.
For any sample of water:
H2O  H3O+ + OH-,
[H2O] = 1mole; [H3O+]= 1.0x10-7mole and [OH-]= 1.0x10-7mole
In 10,000 L of H2O, there would approximately 1/10 of a mL of water- one drop from a
dropper!
If there are 1.0x10-7 atoms of H3O+ (or H+, if you will), then there are the
EXACT same amount of OH- atoms, as well.
This allows water to:
1. be perfectly neutral (barring dissolved substaances, of course)
2. neutralize other substances, to a certain extent, through self-ionization.
1. If an acid-forming ion pops in, the OH- can neutralize it to a
certain extent; the same holds true for bases2. Most solutes are combinations of acid-anhydrides and baseanhydrides; without this characteristic, the solution would cause a
reaction (in theory) as the acids reacted with the bases again;
instead, water dissolves them and separates them.
Ionization of Water:
Kw= [OH-]x[H3O+]
In any sample: OH-= 1.0x10-7;
H3O+=1.0x10-7;
Then multiply:
Kw=1.0x10-14
SO- for a solution to be perfectly neutral, it must have equal amounts of OH- and H3O+
ions.
For instance:
0.001 M NaOH: Basic or Acid? How do you know?
The pH Scale:
A measure of the acidity or basicity of a solution, based on the concentration of
the Hydrogen Ion in solution.
Based on a 0-14 scale. Where does the 14 come from? (Kw).
The smaller the number, the more powerful the acid. The larger the number, the
more powerful the base.
The p OH scale: The OPPOSITE of the pH scale. If you add the pH and the pOH
of a solution, you will always end up with what number? <14>
Why 14?
Because we want to compare pH to water—which always has 1.0 x10^-14
So—[H+] [OH-] = Kw and Kw= 1.0x 0^-14
More pH scale: the pH of a given solution is equal to the inverse log of the
Hydrogen Ion concentration in a given solution.
We find the pH of a solution by finding the concentration of the H+ (or H3O+) ion
in that solution, then taking the opposite of the power.
pH= “pouvoir Hydrogen” = Power of Hydrogen.
Another view of Acids and Bases:
Bronsted –Lowry
Acids: Proton Donor.
Bases: Proton Acceptor
These definitions are called Conceptual Definitions: They are based upon Interpretation
of facts. They were based upon thinking about the problem and trying to come up with
an easier way of defining the answer.
Calling an acid a proton donor is simpler that listing and describing all 6
characteristics; calling a base a proton acceptor is much easier than describing a base. On
top of this, it also explains quite simply that Acids and bases react so effectively.
NH3+H2O  NH4+ + OHDraw Lewis Dot Structures for this- you can see the bare proton evolve.
Conjugate Acids and Bases
Strengths of Acids chart: p. 565