Question

Give three circumstances in which an EDTA back titration might be necessary

Short answer

The three circumstances where an EDTA back titration is needed.

1. Precipitation of analyte in absence of EDTA
2. If the reaction is too slow with EDTA
3. If the indicator is blocked

Step-by-step solution

EDTA

EDTA, also known as ethylenediaminetetraacetic acid forms strong complexes with metal ions and plays a major role in quantitative analysis. In industries it is used as a metal binding agent and used in production of detergents, cleaning agents, food additives etc.

Back Titration

In case of a direct titration an analyte is generally titrated with a standard solution of EDTA. Whereas in case of a back titration an excess amount (known amount) of EDTA is added with the analyte. The excess amount of EDTA takes part in a titration reaction with a solution of second metal ion.

Three circumstances in which an EDTA back titration is necessary

The three circumstances where an EDTA back titration is needed.

a) Precipitation of analyte in absence of EDTA

b) If the reaction is too slow with EDTA

c) If the indicator is blocked