Chapter 10: Acid-Base Titration

Titrating strong base…

with strong acid

Titrating strong acid

with strong base

Titrating weak base

with strong acid

Titrating weak acid

with strong acid

strong base with strong acid

1. Before = pH is determined by the excess OH-

2. At equivalence point = OH- + H+ = H2O, pH is determined by water dissociation

3. After = pH is determined by excess H+

equivalence point

when added titrant is exactly enough for stoichiometric reaction with the analyte

• ideal result in a titration

end point

marked by a sudden physical change, such as an indicator color or an electrode potential

The pH is not 7.00 at the equivalence point in the titration of weak acids or bases. Only when the titrant and analyte are both strong (strong acid, strong base reaction)

TRUE

Before the equivalence point, there is a mixture of HA and A-, which is a buffer..

TRUE

A mixture of HA and A- in any solution,

you have a buffer!

weak acid with strong base

1. solution just contains the weak acid, HA, in water; pH determined by the equilibrium

2. Before = a mixture of unreacted HA plus the A- produced, which means a buffer! Henderson-Hasselbalch equation is used

3. At the equivalence point, HA turned into A-; pH of the weak base is determined by A- + H2O = HA + OH-

4. Beyond = base is in excess and determines pH; calculate pH as if excess bases is added to water; the effect of A- is negligible. 

As the acid gets weaker or more dilution, the end point becomes less distinct

TRUE

weak base with strong acid

1. Before acid is added, solution contains just the weak base, B, in water

2. Before = a mixture of B and pH+

3. At the equivalence point, B converted into BH, a weak acid, It is an acid dissociation reaction of BH.

4. After = excess strong acid determine pH. Neglect BH

Acid-Base indicator

an acid or base with different colors for various protonated species