Weigh out (in triple) accurately approximately 600,0 mg of the Mohr’s salt in a weighing box.
Transfer it to a 300 ml conical flask and dissolve the Mohr’s salt.
Add with a measuring cylinder 35 ml 2 M sulphuric acid and dillute till approximate 150 ml with deionised water.
Add with a measuring cylinder 5 ml concentrated phosphoric acid.
Add , with an interval of 1 minute, 2 portions of approximately 0.2 grams of sodiumhydrogencarbonate and swirl.
Titrate, after the carbon dioxide no longer occures, with the standard 0.02 M MnO4--solution to the first permanent faint pink colour.
Repeat this titration at least two times until you get a correct titre.
Titrate a blanc (in triple).
Calculate the titre of the KMnO4