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Flashcards in Chapter 11 Deck (17)
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1

auxiliary complexing agent

A species, such as ammonia, that is added to a solution to stabilize a metal ion and keep that metal in solution. It binds loosely enough to be displaced by a titrant.

2

back titration

One in which an excess of standard reagent is added to react with analyte. Then the excess reagent is titrated with a second reagent or with a standard solution of analyte.

3

blocking

Occurs when a metal ion binds tightly to a metal ion indicator. A blocked indicator is unsuitable for a titration because no color change is observed at the endpoint.

4

chelate effect

The observation that a single multidentate ligand forms metal complexes that are more stable than those formed by several individual ligands with the same ligand atoms.

5

chelating ligand

A ligand that binds to a metal through more than one atom.

6

complexometric titration

One in which the reaction between analyte and titrant involves complex formation.

7

condtional formation constant

Equilibrium constant for formation of a complex under a particular state set of conditions, such as pH, ionic strength, and concentration of auxiliary complexing species.

8

demasking

Removal of a masking agent from the species protected by the masking agent.

9

direct titration

One in which the analyte is treated with titrant and the volume of titrant required for complete reaction is measured.

10

displacement titration

An EDTA titration procedure in which analyte is treated with excess MgEDTA2- to displace Mg2+. The liberated Mg 2+ is then titrated with EDTA. This procedure is useful if there is no suitable indicator for direct titration of M(n+).

11

formation constant

Equilibrium constant for the reaction of a metal with its ligands to form a metal-ligand complex.

12

indirect titration

One that is used when the analyte cannot be directly titrated. For example, analyte A may be precipitated with excess reagent R. The product is filtered, and the excess R washed away. Then AR is dissolved in a new solution, and R can be titrated.

13

masking agent

A reagent that selectively reacts with one (or more) components of a solution to prevent the components from interfering in a chemical analysis.

14

metal ion indicator

A compound that changes color when it binds to a metal ion.

15

monodentate

A ligand that binds to a metal ion through only one atom.

16

multidentate

A ligand that binds to a metal ion through more than one atom.

17

stability constant

Same as formation constant.