Chapter 11

Question 1

auxiliary complexing agent

Answer 1

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.

Question 2

back titration

Answer 2

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.

Question 3

blocking

Answer 3

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.

Question 4

chelate effect

Answer 4

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.

Question 5

chelating ligand

Answer 5

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

Question 6

complexometric titration

Answer 6

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

Question 7

condtional formation constant

Answer 7

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.

Question 8

demasking

Answer 8

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

Question 9

direct titration

Answer 9

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

Question 10

displacement titration

Answer 10

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+).

Question 11

formation constant

Answer 11

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

Question 12

indirect titration

Answer 12

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.

Question 13

masking agent

Answer 13

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

Question 14

metal ion indicator

Answer 14

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

Question 15

monodentate

Answer 15

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

Question 16

multidentate

Answer 16

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

Question 17

stability constant

Answer 17

Same as formation constant.