In a back titration an excess of titrant is added to the sample. After a sufficiently long waiting time, this excess is then titrated with a second titrant. The difference between the added amount of the first and second titrant then gives the equivalent amount of the analyte.

What is back titration example?

BACK TITRATION Back titration is a process in which the excess of a standard solution used to consume an analyte is determined by titration with a second standard solution. Example: Determination of acetylsalicylic acid in aspirin. Sometime direct titration of an analyte with a reagent is not FEASIBLE.

Why nickel is back titrated with EDTA?

Nickel is titrated with EDTA against murexide. At the beginning of the titration solution should have low ammonia concentration, increased near the end point. This procedure enhances color change at the end point. … EDTA reacts in the same conditions with Cu2+ and Co2+ as well.

What are the types of complexometric titration?

Direct titration: the cations are titrated directly with standard solution EDTA using eriochrome black T as the indicator. Back titration: a known excess of standard solution EDTA is added to the solution containing the analyte.

What happens in a back titration?

During a back-titration, an exact volume of reagent B is added to the analyte A. Reagent B is usually a common titrant itself. The amount of reagent B is chosen in such a way that an excess remains after its interaction with analyte A. This excess is then titrated with titrant T.

What is the difference between titration and back titration?

The key difference between titration and back titration is that in a titration, we usually add a chemically equal amount of standard solution to the analyte whereas, in a back titration, we add an excess amount of standard solution to the analyte.

How is back titration different from direct titration?

In a direct titration, you add a standard titrant to the analyte until you reach the end point. In a back titration, you add an excess of standard titrant to the analyte, and then you titrate the excess titrant to determine how much is in excess.

Why is it necessary to have the titration at about pH 10?

pH 10 buffer is used in EDTA titration because in EDTA Y4- is predominant, and we want Y4- to react with the metal ions that are present in the titration solution. This can be achieved by using a pH 10 buffer.