Acid, Base Equilibrium
metal oxide: basic oxides
-X has low electronegativity -O-X bond is ionic -X is likely dissociated by polar water
water is amphoteric
-can act as an acid or a base -water autoionizes Kw=[H+][OH-] and product equals 1.0X10-14
ions with acidic behavior include
-cations that are conjugate acids of weak bases -metal cations with +2 or +3 charge
Ions with neutral behavior (no ability to act as acid or base)
-conjugate bases of strong acids -alkali metal or alkaline metal cations (other half of strong bases)
Ions with basic behavior include
-conjugate bases of weak acids
kw has different values at different temperatures
-dissociation of water is endothermic, so as T increase kw will increase
factors for acidity in non-binary compounds (oxyacids)
-for related acids, acid strength increases with an increase in number of atoms on central atom (extra O atoms increase polarity of H-O bond) -for nonrelated acids, acid strength increases with electronegativity of central bond
nonmetal oxide: acidic oxides
-interaction with oxide in water that makes it acidic -when H-O-X group is dissolved in water, O-X bond stays intact and the polar H-O bond breaks
Weak Acid definition
-ionization equilibrium lies far to the left -yields a strong conjugate base -anion is stronger base than water
Strong Acid definition
-ionization equilibrium lies far to the right -yields a weak conjugate base -water is a stronger base than anion
when is equilibrium is reached?
-when acids and bases ionize
Weak Acid: strength of conjugate base compared with that of water
Anion much stronger base than water
Strong Acid: strength of conjugate base compared with that of water
Anion much weaker base than water
Strong Acids List
HCl, HBr, HNO3, H2SO4, HI, HClO4
Weak Acid: equilibrium [H+] compared with original concentration of HA
[H+] << [HA]
Strong Acid: equilibrium [H+] compared with original concentration of HA
[H+] = ~[HA]
conjugate acid of weak base + neutral
acidic
neutral cation + conjugate base of weak acid
basic
conjugate acid of weak base + conjugate base of weak acid
depends on Ka or Kb value
Weak Acid: position of the dissociation equilibrium
far to the left
Strong Acid: position of the dissociation equilibrium
far to the right
bond polarity
high polarity, whatever proton leaves behind, is more stable with electron then it is more acidic
Strong Acid: ka value
ka large
acidity factor
need to consider what would make the proton more labile (more likely to be separated from the rest or the molecule)
neutral cation + neutral anion yeilds
neutral acid or base
significant figures of logs
number of decimal places in the log is equal to the number of significant figures in the original concentration value
Weak Acid: ka value
weak
bond strength
weaker bond is more labile- easier to break so it is a stronger acid as it will dissociate
