MIDTERM 01 - Complexation Titrations Flashcards
These are a class of reactions that deal with complex formation
Complexation reaction
Resulting complex when a ligand contains two or more molecules/groups that can donate electrons
Cheleate
Electron donor
Ligand
Electron acceptor
Metal ion
Most commonly used analytical reagent for complexation reaction
Na2EDTA
When a ligand binds to a metal ion through only one atom
Monodentate
When a ligand binds to a metal through two atoms
Bidendate
When a ligand binds to a metal ion through four atoms
Tetradentate
When a ligand binds to a metal ion through six atoms
Hexadentate
When a ligand binds to a metal ion through eight atoms
Octadentate
When a ligand binds to a metal ion through more than one ligand atom
Multidentate/chelating ligand
Ammonia
Monodentate
Water
Monodentate
Halides
Monodentate
Glycine
Bidentate
Ethylenediamine
Bidentate
Nitriloacetic acid (NTA)
Tetradentate
Ethylenediaminetetraacetic acid (EDTA)
Hexadentate
Egtazic acid
Hexadentate
Diethylenetriaminepentaacetic acid (DTPA)
Octadentate
Equilibrium constant for the reaction of a metal with a ligand
Function constant/stability constant
Ability of ligands to form more stable metal complexes
Chelate effect
Association constant of a chemical reaction
pKn value/Kn
Used in EDTA titrations; these are organic compounds which form colored complex ions with metal ion
Metallochromic indicators
Type of titration (Standardization of 0.05 M Na2EDTA)
Direct titration
Type of titration (Standardization of 0.05 M ZnSO4.7H20)
Direct titration
Analyte (Standardization of 0.05 M Na2EDTA)
Chelometric calcium carbonate
Analyte (Standardization of 0.05 ZnSO4.7H2O)
Na2EDTA
Volumetric solution (Standardization of 0.05 M Na2EDTA)
0.05 M Na2EDTA
Volumetric solution (Standardization of 0.05 M ZnSO4.7H2O)
0.05 M ZnSO4.7H2O
Buffer (Standardization of 0.05 M Na2EDTA)
NaOH
Buffer (Standardization of 0.05 M ZnSO4.7H2O)
Acetic-acid ammonium acetate
Indicator (Standardization of 0.05 M Na2EDTA)
Hydroxynaphthol blue
Indicator (Standardization of 0.05 M ZnSO4.7H2O)
Dithizone
Color transition (Standardization of 0.05 M Na2EDTA)
Red to blue
Color transition (Standardization of 0.05 M ZnSO4.7H2O)
Green to rose pink
Purpose of using distilled water
Because there is no presence of dissolved ions in distilled water
Purpose of drying at 110°C
To remove moisture
Purpose of cooling in desiccator
To ensure the right temperature
Purpose of diluted hydrochloric acid (HCl)
To dissolve the calcium carbonate (CaCO3)
Purpose of using sodium hydroxide TS as a buffer
So that that complex would be stable and any magnesium present as a contaminant would not react
Purpose of using acetic acid ammonium acetate as a buffer
Since dithizone gives a transition color at this condition
Purpose of using amber bottle in storing ZnSO4 standard solution
Because zinc sulfate is sensitive to heat
Is a method in which unwanted purities in the analyte are masked by chemical reagents
Masking
Is a compound capable of forming a complexation reaction at a favorable pH condition
Masking agent