Virtual CrezLab - Qualitative Analysis

TEACHING LABORATORY

Chemical Reactions

	Redox Reactions/ Displacement
	Neutralisation reaction
	Displacement reaction

VIRTUAL CHEMLAB

PERFORMANCE LABORATORY

The Laboratory
Challenge

The MCQ Challenge

ChemQuest

VIRTUAL CHEMLAB

Redox Lab Manual

I. Test for Oxidising Agents

b) Using Sodium thiosulphate as the reducing agent

Sodium thiosulphate is a common reducing agent used to reduce brown iodine solution (an oxidizing agent) to colourless iodide solution.

3a) To a portion of reddish brown solution, R add sodium thiosulphate until further change is observed.

Observations

Reddish brown solution is decolourised.

Chemical reaction

Redox reaction.

The brown solution R is likely to be iodine solution.

Sodium thiosulphate has reduced brown iodine molecules, I₂, to colourless iodide ions, I^-.

Iodine molecules gained electrons to become reduced to iodide ions.

I₂ (aq) + 2e^- -----> 2I^- (aq)