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U-4
These results show that it is possible to establish the nature of the bonding within a given oxide 
(i.e. covalent or ionic bonding) simply by reacting the oxide with water and measuring the pH of the resulting
solution. 
The strength of a weak acid (i.e. one that does not completely dissociate in water) is measured quantitatively by
the magnitude of the acid dissociation constant, K
a
:
HA
(aq)
  +  H2O
(l) 
  H3O
+
(aq)
  +  A
-
(aq)
K
a
  = 
[H3O
+
][A
-
]
[HA]
The larger the value for the K
a
, the further the equilibrium lies to the right and hence the stronger the acid.
One of the most important factors affecting the position of the acid dissociation equilibrium is the stability of the
anion.  By stabilizing the anion through charge delocalization, the acidity of the conjugate acid can be enhanced. 
One way to delocalize charge, and increase acidity is to introduce electron withdrawing substituents into the acid
at positions close to the proton-bearing group.  These substituents help to stabilize the anion by pulling some of the
electron density away from the electronegative element² bearing the labile proton.  Compare for instance, the
acidity of acetic acid with chloroacetic acid.
H3CCOOH
K
a
1.74 x 10
-5
H2ClCCOOH
K
a
= 1.38 x 10
-3
By substituting just one hydrogen with an electron withdrawing chlorine, the acid strength increases by nearly two
orders of magnitude!
EXPERIMENTAL METHOD
In Part I of the experiment, the effects of the nature of intramolecular chemical bonding on the solubility of both
ionic and nonpolar compounds in water (a polar solvent) and in dichloromethane (a nonpolar solvent) will be
examined.  A conductivity detector will be used to check for the presence of dissolved ions.  The light on the
detector will glow more intensely as the concentration of ions in solution increases.  The reason for this is that as
the number of dissolved ions increases, more current can be carried by the solutions.  This is manifested as a
                                                                                                                                                                                                                                
2.
Oxygen is the electronegative element bearing the labile proton in all of the acids studied in this experiment.
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