Exact reason to use ammonia buffer in estimation of hardness2 pointsto maintain high pHEDTA complex is stable at that pHto maintain low pHNone

Exact Reason to Use Ammonia Buffer in Estimation of Hardness

1. To Maintain High pH: The primary reason for using an ammonia buffer in the estimation of hardness, particularly in complexometric titrations with EDTA, is to maintain a high pH. At elevated pH levels, the EDTA complex is stable, which is crucial for accurately quantifying the hardness of water. It prevents the formation of polyprotic acid complexes and ensures that the EDTA can effectively complex with the metal ions present in the sample.

2. Stabilization of EDTA Complexes: In a high pH environment, the protonation of EDTA is minimized, allowing more of the unprotonated EDTA to remain in its active form. This stability is essential for reliable measurements during titration, as fluctuations in pH could lead to erroneous results by affecting the degree to which EDTA can complex with calcium, magnesium, and other divalent cations responsible for water hardness.

In conclusion, the ammonia buffer serves to maintain the necessary high pH to ensure the stability and effective functioning of EDTA during titrations that estimate hardness.