For the following lab Complexometeric Determination of Magnesium... Mg^2+ + Y^4- -> MgY^2- Unknown MgO was titrated with roughly 0.03M of Na2EDTA and pH10 buffer solution (~5mL to MgO) using Nh4CL(s) and NH4OH, 8 drops of Calmigate Indictor and titrated to a blue endpoint with the EDTA (disappearance of the last tinge of red) 1. Titration of Zn^2+ and EDTA is carried out in the same manner as Mg^2+ - EDTA titration (Zn can actually be used to standardize EDTA solution). In this case the ammonia from the pH 10 buffer serves an additional purpose. What is it? 2. If the unknown consisted of Co+2, Fe+2, Sr+2, and Ni+2, which cation would completely complex with the EDTA first? Second? Third? Fourth? (State your reasons!) Also what are the minimum pH values required for satisfactory titrations of the above metal cations? (How know?) 3. Briefly (but specifically) discuss how the Calmagite indicator works.
For the following lab Complexometeric Determination of Magnesium...
Mg^2+ + Y^4- -> MgY^2-
Unknown MgO was titrated with roughly 0.03M of Na2EDTA and pH10 buffer solution (~5mL to MgO) using Nh4CL(s) and NH4OH, 8 drops of Calmigate Indictor and titrated to a blue endpoint with the EDTA (disappearance of the last tinge of red)
1. Titration of Zn^2+ and EDTA is carried out in the same manner as Mg^2+ - EDTA titration (Zn can actually be used to standardize EDTA solution). In this case the ammonia from the pH 10 buffer serves an additional purpose. What is it?
2. If the unknown consisted of Co+2, Fe+2, Sr+2, and Ni+2, which cation would completely complex with the EDTA first? Second? Third? Fourth? (State your reasons!) Also what are the minimum pH values required for satisfactory titrations of the above metal cations? (How know?)
3. Briefly (but specifically) discuss how the Calmagite indicator works.
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