Study Set Content:
Indicator used:
potassium chromate
Sample assays:
Sodium lauryl for chloride content
ex. of volhar method
at the end point, the excess thiocyanate will react with FAS forming a red complex (ferric thiocyanate)
at the end point, the excess thiocyanate will react with FAS forming a red complex (ferric thiocyanate)
ex. of Mohr Method
When a chloride content will react to silver nitrate to form a white precipitate, when the chloride is completely precipitated a drop of silver nitrate in excess will react with the indicator (chromate ion), forming a brownish red ppt.
Involves formation of a blue precipitate
Liebig method
Standard solution:
Sodium tetraphenylboron
Indicator used:
Bromophenol blue
Sample assay:
Assay of Organic nitrogen compounds
Involves cessation of precipitate or turbidity.
– This makes a technique where a fluid was drawn off from a reaction mixture and it is placed on a spot plate. A drop of titrant is added. If turbidity of precipitate is formed the process is continued. This method is prone to error.
Gay-lussac method (equal turbidity method)
Standard solution:
silver nitrate
Indicator used:
None
Sample assay:
Sodium chloride
Based on the oxidation reduction reactions between the analyte and the titrant.
Redox titrations
- can be standardized easily and retains its concentration over long periods of time if it is protected from sunlight and entry of organic matter.
KMnO4 solutions
- KMnO4 solutions can be standardized easily and retains its concentration over long periods of time if it is protected from sunlight and entry of organic matter.
Permanganate Method (Permanganometry)
It also serves as its own indicator
pale pink color
Sample Assays: Permanganate Method (Permanganometry)
H2O2 solution (direct); Malic Acid in Cherry Juice (indirect); K nitrite, Na nitrite, Pb monoxide (residual)
A solution of ceric sulfate in dilute sulfuric acid is a strong oxidizing agent and considerably more stable than standard permanganate solutions, provided enough sulfuric acid is present to prevent hydrolysis and precipitation.
- Ceric Sulfate Titration Method (Cerimetry)
It can be self-indicating since the solution appears as a yellow solution.
- Ceric Sulfate Titration Method (Cerimetry)
Primary Standard:
Arsenic trioxide (old); Na oxalate (new)
