PART 2 - PRECIPITATION, COMPLEXATION & REDOX TITRATIONS

Redox

• Electrons are transferred from one reactant to another

• Involves a change in valence

redox titrimetric analysis

Similar to acid-base neutralizations, there is opposition with regard to the nature of the titrant and titrand.

permanganometry

• uses KMnO₄ standard solutions

• standardized easily

• retains concentration over long periods

sodium oxalate

primary standard of permanganometry

oxalic acid

sodium oxalate + sulfuric acid = __________

autocatalysis

reaction process becomes more rapidly a.k.a. _________

(permanganometr)

none

indicator of permanganometry

self indicator

KMnO₄ is a ________

permanent faint pink

preferred end point of permanganometry

iodine solution

• a weak oxidizing agent

• used for the determination of strong reducing agents

• not very water soluble (1g:2950 mL)

KI (potassium iodide)

used as a solubilizing agent in iodine method

direct titration (iodimetry)

• using iodine as titrant

• used in the assay of

  • strong iodine solution

  • ascorbic acid

reducing agent

analyte of iodimetry

starch

indicator of direct and residual titration of iodimetry

excess

residual titration using iodine as _______

sodium thiosulfate

back titrant of residual titrant of iodine (as excess)

methionine

cupric sulfate

residual titration using iodine (as excess) are used in the assay of _______

bluish-black

preferred end point of direct titration using iodine as titrant

colorless

preferred end point of residual titration of iodine (as excess)

iodometry

• Indirect titration of iodine liberated produced by the oxidation of iodide, and determined by standard solutions such as Sodium thiosulfate

• indirect analysis of oxidizing agent

1N Bromine solution

aka Koppescharr’s solution

bromine method

• The solution contains an equivalent amount of potassium bromate and excess potassium bromide

• alternative for iodine method

  • used in the assay of compounds like aniline, phenol and resorcinol