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M.A.R.
M.A.R.
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In my next lab, I'll be doing a complexometric titration of a copper solution with EDTA and a murexide indicator. The lab guide advises to keep the pH level nearly neutral by adding a diluted $NH_3$$\ce{NH3}$ solution. Why is that necessary?

I understand that during the formation of the copper complex $[Cu(EDTA)]^{2-}$$\ce{[Cu(EDTA)]^{2-}}$, the solution becomes more acidic. Do we need to add the basic solution in order to make sure the murexide does not change color due to the decreasing pH level? Or is it simply so that we can revert the color change (of the formation of the copper complex) and continue the titration until the equivalence point is reached (and all copper ions are in complex form)?

In my next lab, I'll be doing a complexometric titration of a copper solution with EDTA and a murexide indicator. The lab guide advises to keep the pH level nearly neutral by adding a diluted $NH_3$ solution. Why is that necessary?

I understand that during the formation of the copper complex $[Cu(EDTA)]^{2-}$, the solution becomes more acidic. Do we need to add the basic solution in order to make sure the murexide does not change color due to the decreasing pH level? Or is it simply so that we can revert the color change (of the formation of the copper complex) and continue the titration until the equivalence point is reached (and all copper ions are in complex form)?

In my next lab, I'll be doing a complexometric titration of a copper solution with EDTA and a murexide indicator. The lab guide advises to keep the pH level nearly neutral by adding a diluted $\ce{NH3}$ solution. Why is that necessary?

I understand that during the formation of the copper complex $\ce{[Cu(EDTA)]^{2-}}$, the solution becomes more acidic. Do we need to add the basic solution in order to make sure the murexide does not change color due to the decreasing pH level? Or is it simply so that we can revert the color change (of the formation of the copper complex) and continue the titration until the equivalence point is reached (and all copper ions are in complex form)?

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DK2AX
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Why should a complexometric titration be kept neutral?

In my next lab, I'll be doing a complexometric titration of a copper solution with EDTA and a murexide indicator. The lab guide advises to keep the pH level nearly neutral by adding a diluted $NH_3$ solution. Why is that necessary?

I understand that during the formation of the copper complex $[Cu(EDTA)]^{2-}$, the solution becomes more acidic. Do we need to add the basic solution in order to make sure the murexide does not change color due to the decreasing pH level? Or is it simply so that we can revert the color change (of the formation of the copper complex) and continue the titration until the equivalence point is reached (and all copper ions are in complex form)?