Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
-----------------
stannous chloride : SnCl2
sodium sulfite : Na2SO3
sodium persulfate : Na2S2O8
hydrochloric acid : HCl
potassium tetrachloroplatinate (II) : K2PtCl4
Class:
------
elem=Pt
redox
Summary:
--------
Platinum (II) can be oxidized to platinum (IV) by strong oxidizing agents.
Reduction to metallic platinum cannot be achieved by sulfite nor by stannous
chloride.
Description:
------------
Add some solid sodium persulfate to a solution of K2PtCl4 in dilute HCl (appr.
5% by weight): The liquid remains light red/brown (typical color of dilute
[PtCl4]2-) and the solid dissolves.
Heat the liquid: The liquid becomes yellow. The color is much more intense
than the original red/brown.
Add an excess amount of a solution of sodium sulfite: The liquid becomes
lighter, almost colorless. There is a strong smell of SO2.
Boil the liquid for a while: The SO2 is driven off, the appearance of the
liquid does not change. There is no reduction to metallic platinum.
Add some solid tin chloride to the still warm liquid: The solid quickly
dissolves. The liquid becomes turbid and yellow/ochre/brown.
Add some 10% HCl: The liquid becomes completely clear and the color of the
liquid becomes yellow/brown. In the course of a minute, the liquid becomes
lighter, it becomes yellow.
Add more tin chloride: This dissolves, the liquid becomes yellow/brown again
and a little bit turbid.