Saturday, November 19, 2011

Chemistry: How to Solve Titration Questions

Strong Acid + Strong Base Titration
  1. Convert concentrations to number of moles
  2. Subtract the smaller n from the larger n
  3. Calculate -log (difference÷total volume)
  4. If the larger n is of the acid, the result is the pH. Otherwise, it's the pOH.

Weak Acid+ Strong Base Tritation

If there's more weak acid than strong base:
  1. Subtract the two n's.
    • conjugate base = n strong base ÷ total volume
    • weak acid = difference ÷ total volume
  2. Using the ICE table and the ka, calculate the new concentration of H+
  3. pH=-log (H+)
If there's an equal amount of acid and base
  1. conjugate base= n strong base ÷ total volume
  2. kb = kw ÷ ka
  3. [OH-] = square root of (kb* Cconjugate base)
  4. pH = 14 + log [OH-]
If there's more strong base than weak acid
  1. Find the difference between the two n's
  2. Divide the difference by the total volume
  3. pH = 14 + log [quotient]

Weak base+ Strong Acid Tritation
The steps are the same as those of Weak Acid+ Strong Base Tritation.