Description

Ferroin Indicator 500mL

Ferroin indicator is a solution commonly used in analytical chemistry for redox (reduction-oxidation) titrations. It’s a 0.025 molar (M) solution, meaning there are 0.025 moles of the indicator complex per liter of solution. The solution is typically contained in a 500 mL amber glass bottle.

Components:

• Phenanthroline (1,10-phenanthrolin-5(6)-amine): This organic compound forms a complex with ferrous iron (Fe²⁺) ions, giving the solution a faint orange-red color.
• Ferrous sulfate (FeSO₄): This salt provides the ferrous iron (Fe²⁺) ions that complex with phenanthroline.
• Water (H₂O): The solvent that dissolves the other components.

Function in Redox Titrations:

During a redox titration, one reactant gains electrons (reduction) while another loses electrons (oxidation). Ferroin acts as a visual indicator for the endpoint of the titration, which is the point at which all the available reactant in one solution has reacted with the titrant (the solution being added dropwise).

• Before the endpoint: When the solution being titrated contains excess Fe²⁺ ions, they complex with phenanthroline, giving the solution the orange-red color.
• At the endpoint: When all the Fe²⁺ ions in the solution being titrated have reacted, there are no free Fe²⁺ ions available to complex with phenanthroline. The indicator complex dissociates, and the solution turns a pale blue-green color. This color change signifies the endpoint of the titration.

Applications:

• Chemical Oxygen Demand (COD) Determination: This method measures the amount of organic matter in water that can be biologically oxidized by microorganisms. Ferroin is used as an endpoint indicator in the titration step of COD analysis.
• Other Redox Titrations: Ferroin can be used as an indicator for various other redox titrations involving iron or other oxidants/reductants that can react with Fe²⁺ ions.