Which of the following experiments can be described as a displacement titration? A. Calcium in powdered milk is determined by dry ashing a 1.50 g sample and then titrating the calcium with 12.1 mL of 0.008949 M EDTA. B. The Tl in a 9.57-g sample of rodenticide was oxidized to the trivalent state and treated with an unmeasured excess of Mg/EDTA solution. The reaction is Tl3+ + MgY2- -> TlY- + Mg2+ Titration of the liberated Mg2+ required 12.77 mL of 0.03610 M EDTA. C. A 3.650-g sample containing bromide was dissolved in sufficient water to give 250.0 mL. After acidification, silver nitrate was introduced to a 25.00-mL aliquot to precipitate AgBr, which was filtered, washed, and then redissolved in an ammoniacal solution of potassium tetracyanonickelate(II): Ni(CN)42- + 2AgBr(s) -> 2Ag(CN)2- + Ni2+ + 2Br- The liberated nickel ion required 26.73 mL of 0.02089 M EDTA. D. A solution contains 1.569 mg of CoSO4 (155.0 g/ mol) per milliliter. 50.00 mL of 0.007840 M EDTA was added to a 25.00-mL aliquot of the CoSO4 solution. The unreacted EDTA was titrated with 0.009275 M Zn2+.
Which of the following experiments can be described as a displacement titration?
A.
Calcium in powdered milk is determined by dry ashing a 1.50 g sample and then titrating the calcium with 12.1 mL of 0.008949 M EDTA.
B.
The Tl in a 9.57-g sample of rodenticide was oxidized to the trivalent state and treated with an unmeasured excess of Mg/EDTA solution. The reaction is Tl3+ + MgY2- -> TlY- + Mg2+
Titration of the liberated Mg2+ required 12.77 mL of 0.03610 M EDTA.
C.
A 3.650-g sample containing bromide was dissolved in sufficient water to give 250.0 mL. After acidification, silver nitrate was introduced to a 25.00-mL aliquot to precipitate AgBr, which was filtered, washed, and then redissolved in an ammoniacal solution of potassium tetracyanonickelate(II): Ni(CN)42- + 2AgBr(s) -> 2Ag(CN)2- + Ni2+ + 2Br-
The liberated nickel ion required 26.73 mL of 0.02089 M EDTA.
D.
A solution contains 1.569 mg of CoSO4 (155.0 g/ mol) per milliliter. 50.00 mL of 0.007840 M EDTA was added to a 25.00-mL aliquot of the CoSO4 solution. The unreacted EDTA was titrated with 0.009275 M Zn2+.
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