Using Figure 17.11, suggest an indicator to use in each of the following titrations:

1. (a) The weak base pyridine is titrated with HCl.
2. (b) Formic acid is titrated with NaOH.
3. (c) Ethylenediamine, a weak diprotic base, is titrated with HCl.

Figure 17.11 Common acid-base indicators. The color changes occur over a range of pH values. Notice that o few indicators hove color changes over two different pH ranges.

Interpretation:

The weak base pyridine is titrated with HCl, an indicator used has to be determined.

Concept introduction:

A titration is one of the most useful ways of determining accurately the quantity of an acid, a base or some other substances in a mixture.

The pH at the equivalence point of a strong acid –strong base titration is 7.

A weak acid titrated with a strong base leads to a pH > 7 at the equivalence point.

A weak base titrated with a strong acid leads to pH < 7 at the equivalence point.

Indicators:

A chemical substances which gives a visible change  in the titration.

Some important indicators are as follow.

Pyridine is a weak base and has a pkb= 8.82. Titrating a weak base with a strong acid HCl.

Therefore, the resultant solution pH will be less than the 7

Interpretation:

Formic acid is titrated with NaOH , an indicator used has to be determined.

Concept introduction:

A titration is one of the most useful ways of determining accurately the quantity of an acid, a base or some other substances in a mixture.

The pH at the equivalence point of a strong acid –strong base titration is 7.

A weak acid titrated with a strong base leads to a pH > 7 at the equivalence point.

A weak base titrated with a strong acid leads to pH < 7 at the equivalence point.

Indicators:

A chemical substances which gives a visible change  in the titration.

Some important indicators are as follow.

Interpretation:

Ethylene diamine, a weak diprotic base, is titrated with HCl, an indicator used has to be determined.

Concept introduction:

A titration is one of the most useful ways of determining accurately the quantity of an acid, a base or some other substances in a mixture.

The pH at the equivalence point of a strong acid –strong base titration is 7.

A weak acid titrated with a strong base leads to a pH > 7 at the equivalence point.

A weak base titrated with a strong acid leads to pH < 7 at the equivalence point.

Indicators:

A chemical substances which gives a visible change  in the titration.

Some important indicators are as follow.