Scribd
Upload
2K views1 page

Determination of Copper: Direct Titration Using Murexide As Indicator

This document describes a method for determining copper using direct titration with EDTA and murexide indicator. Murexide is purple when free but turns yellow when complexed with copper. The copper-EDTA complex is titrated until the solution changes from yellow/green to purple, indicating the endpoint of the reaction. The method can accurately determine copper concentrations up to 25 mg in 100 mL solutions.

Uploaded by

ajali1957
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
2K views1 page

Determination of Copper: Direct Titration Using Murexide As Indicator

This document describes a method for determining copper using direct titration with EDTA and murexide indicator. Murexide is purple when free but turns yellow when complexed with copper. The copper-EDTA complex is titrated until the solution changes from yellow/green to purple, indicating the endpoint of the reaction. The method can accurately determine copper concentrations up to 25 mg in 100 mL solutions.

Uploaded by

ajali1957
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
You are on page 1/ 1

Determination of Copper: Direct Titration using

Murexide as indicator

PRINCIPLE:
Copper(II) ions can be determined quantitatively by complexometric direct titration with EDTA
in ammoniacal solution. The indicator used is Murexide indicator which is purple when it is free
(H4ln-) and yellow (green) when complexed with copper.

It should be noted that this method is only applicable to solutions containing up to 25 mg copper
ions in l00mL of water; if the concentration of Cu2+ ions is too high, the intense blue color of the
copper (II) ammine complex masks the colour change at the end point. The indicator solution must
be freshly prepared. The copper-murexide complex is pure yellow, but the color at the starting
point of the titration is greenish depending on the amount of copper present. The green is the
mixture of yellow (indicator complex) and blue (copper ions).

REAGENTS:
1- Copper(II) ions solution (analyte)
2- Ammonia solution (1:1) as a buffer pH <9
3- Murexide indicator
4- 0.01 M EDTA solution

PROCEDURE:
1- Pipette 25.0 mL of Copper ions solution into a 250.0 mL and add Add
ammonia solution drop-wise until the light blur precipitate first formed
dissolves to form a clear blue solution and dilute to about 100.0 mL with
distilled water.
2- Add 3 to 4 drops of Murixide indicator.
3- Titrate with 0.01 M EDTA until the color changes from yellow (green) to
purpule. Record the used volume (as VEDTA).
4- Repeat the titration twice.

You might also like