Lecture Six covers the following points:-
- Titration of weak acid and strong base
- Titration of weak base and strong acid
- Titration of weak acid and weak base
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Neutralization of a weak acid with a strong base
• CH3COOH + NaOH = CH3COONa + H2O
• Titration of 50 ml of 0.1 M acetic acid with 0.1 M NaOH
• ( Ka = 1.75 x 10-5 ).
• Initial point: pH= 2.88
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• The effect of reaction completeness:
• Titration curves for 0.1 M solutions of acids with different dissociation constants are shown in Fig. Note that the pH change in the equivalence point region becomes smaller as the acid becomes weaker that is ,as the reaction between the acid and the base becomes less complete.
• Indicator choice:
• The choice of indicator for the titration of weak acid and strong base is more limited than that for a strong acid and strong base.
Neutralization of a weak base with a strong acid
NH4OH + HCl = NH4Cl + H2O
Neutralization of a weak base with a weak acid
The titration curve for the neutralization of weak acid and weak base shows that the change of pH near the equivalence point and during the whole of neutralization curve is very gradual. There is no sudden change in pH and hence no sharp end point can be found with any simple indicator.
- Titration of weak acid and strong base
- Titration of weak base and strong acid
- Titration of weak acid and weak base
-
-
Neutralization of a weak acid with a strong base
• CH3COOH + NaOH = CH3COONa + H2O
• Titration of 50 ml of 0.1 M acetic acid with 0.1 M NaOH
• ( Ka = 1.75 x 10-5 ).
• Initial point: pH= 2.88
•
• The effect of reaction completeness:
• Titration curves for 0.1 M solutions of acids with different dissociation constants are shown in Fig. Note that the pH change in the equivalence point region becomes smaller as the acid becomes weaker that is ,as the reaction between the acid and the base becomes less complete.
• Indicator choice:
• The choice of indicator for the titration of weak acid and strong base is more limited than that for a strong acid and strong base.
Neutralization of a weak base with a strong acid
NH4OH + HCl = NH4Cl + H2O
Neutralization of a weak base with a weak acid
The titration curve for the neutralization of weak acid and weak base shows that the change of pH near the equivalence point and during the whole of neutralization curve is very gradual. There is no sudden change in pH and hence no sharp end point can be found with any simple indicator.