6b.3: Solving

Two Critical Questions:
1. Is my compound an acid or a base?
2. Is it strong or weak?

Strong Acid:
 Because it dissociates completely, [H+] = [acid], so   pH = -log[acid]

Strong Base:
Same principle as acid, but with pOH:       
      pOH = -log[base]    and  pH + pOH = 14
                EXCEPT!!!!
* Oxide makes two hydroxides when dissolved in water--it makes one and becomes one.
* Some compounds have multiple hydroxides--such as calcium hydroxide

In both of these cases, the [OH-] is double the [base].
(In principle, you'd triple it for aluminum hydroxide...if you can somehow get it to dissolve)

Weak Acid:
Write a Ka and do an ICE box to get [H+]. 
Then pH = -log[H+]


Weak Base:
Write a Kb and do an ICE box to get [OH-]. 
Then pOH = -log[OH-] and pH + pOH = 14


However, you will rarely be given Kb. Instead, you need to use the equation:
               Ka*Kb = Kw


Where Ka and Kb are for a conjugate acid-base pair (so you'd look up the Ka of HF if you wanted to get the Kb of F-)