106. EDTA titrations of metal ions are pH sensitive. Which of the following stat

ID: 928115 • Letter: 1

Question

106. EDTA titrations of metal ions are pH sensitive. Which of the following statements is not true?

a) At low pH, the amount of Y4- decreases.

b) As pH is lowered, the end point becomes less distinct.

c) Metals with higher formation constants can be titrated at lower pH.

d) All metals require alkaline titration conditions.

e) At higher pH, the metal hydroxide can precipitate.

107. Which of the following statements is true about an auxiliary complexing agent?

a) increases the conditional formation constant

b) forms a complex with the metal ion

c) protects some components in the mixture from reacting with EDTA

d) forms a complex with the indicator e) displaces the metal ion from the metal–EDTA complex

108. The end point of a complexometric titration cannot be detected by:

a) metal ion indicators.

b) starch-Iodine complex.

c) mercury electrode.

d) ion selective electrode.

e) glass (pH) electrode.

109. When determining pMetal at the equivalence point in a complexometric titration, _______ is used.

a) Kf

b) K’f

c) K’’f

d) Ka

e) Kb

106)e

107)b

108)b

109)b

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