Diphenylamine indicator to be used for the mixture phosphoric and sulphuric acid
Answers
Diphenylamine [(C6H5)2NH] is a relatively SAFE aromatic organic nitrogen compound that has excellent anti-oxidant properties. Diphenylamine has a low acute oral toxicity and it is approved in some food contact applications, so it is safe for use in an undergraduate laboratory where students are known to do stupid things. Diphenylamine is a weak base (pKb = 14) and is moderately soluble in water and freely soluble in common organic solvents. These qualities make it a suitable laboratory reagent.
Diphenylamine is an indicator used in titrations that involve redox reactions, especially those in which potassium chromate (K2CrO4) or potassium dichromate (K2Cr2O7) is used as the oxidizing agent. Diphenylamne is used as an indicator because it shows a very clear color change from green to violet when end point of the titration is reached. Usually phosphoric acid is added to the Fe2+ solution (ferrous ammonium sulfate) if that is the reductant that is being titrated, so that the Fe3+ product may be stabilized.
Explanation:
Diphenylamne is used as an indicator because it shows a very clear color change from green to violet when end point of the titration is reached. Usually phosphoric acid is added to the Fe2+ solution (ferrous ammonium sulfate) if that is the reductant that is being titrated, so that the Fe3+ product may be stabilized.