| Acids | Bases |
| Sour tasting Ex: acetic acid (vinegar) | Bitter Ex: Soaps (most bases inedible) |
| React with metal Ex: Zn in hydrogen lab | Don't react with metal |
| Feel slippery | |
| Conduct electricity | Conduct electricity |
| Release H+ ions in solutions (actually Hydronium H3O+) | Provide or create OH- ions in water. |
| Neutralize bases | Neutralize acids |
| React with some indicator solutions | React with some indicator solutions |
Bronsted-Lowry Theory
Acids are proton donors. Bases are proton acceptors.
So... now this might not be totally obvious but....
The weaker the acid, the stronger the conjugate base. If the conjugate base wants H+ more than water wants the H+ then the acid molecule stays together. This is the definition of a weak acid (mostly stays as a molecule)
HA + H2O <===> H3O+ + A-
acid base C.A. C.B.
proton donor proton acceptor where proton ends acid without proton
Good, high level review. Start with electrolytes and work your way down.
Neutralization
Generic Neutralization
reaction
acid + base ----> salt + water
Example:
HCl + NaOH ----> NaCl + HOH
At Neutralization we know that the strength of the acid times its volume has been exactly matched by the strength of the base times its volume. The strength units must be N (normality) to put everything on even footing. (Many common acids give 2 or even 3
H+ ions per mole, so we can't just use molarity.)
Na x Va = Nb x Vb at the point of Neutralization.
If you want some online practice, try these. Have a calculator handy.
Disassociation of Water
Water: must be
present to have either acids or bases.
K(w) = 10-14 always always always.That means 1 in a hundred trillion
molecules of water falls apart, or disassociates into H+ + OH-.
This value is a constant at 25 C.
So [H+] x [OH-] = 10-14 always.
So in neutral solutions
[H+] x [OH-} =
10-14
Where are [H+] and [OH-] equal?
[10-7] x [10-7] or pH = 7
If one goes up, then the other must go down!
This means that pH+ pOH = 14 always !!!!!
Another result of this is that Ka x Kb = Kw
Calculations
Given molarity of an acid (concentration of H+):
Want pH :
1) take log of concentration
2) change sign (drop negative)
Given pH:
Want [H+] (the concentration of H+):
1) change sign of pH to negative
2) antilog that negative number: 10-pH
Given pH:
Want pOH:
1) 14-pH = pOH
Given [OH-]:
Want pOH:
1) log of [OH-]
2) change sign (drop negative)
Given pOH:
Want [OH-]:
1) change the sign of pOH
2) antilog that negative number 10 -pOH