Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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nitric acid : HNO3
hydrochloric acid : HCl
tin : Sn
Class:
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elem=Sn
redox
Summary:
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Tin metal does not dissolve quickly in concentrated hydrochloric acid.
Tin metal only slowly dissolves in aqua regia.
The solution obtained is clear.
Description:
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Add some very pure tin metal (99.99+ %) in the form of a 'drop' (2 mm diameter)
to some 30% HCl: At first glance no reaction occurs. After a minute or so, a
very slow evolution of a gas can be observed. Tiny bubbles of gas are evolved
at the metal surface.
Heat the acid with tin to approximately 60 C: The evolution of gas goes a
little bit faster, but it remains very slow.
Allow the tin in the concentrated acid to stand for one day: After one day,
hardly any tin is dissolved. The 'drop' of tin is almost as large as when the
experiment started. The surface of the metal has become more dull and grey.
Before the experiment it was light and shiny. The liquid still is clear and
colorless.
Add approximately 1/3 of volume of 52% HNO3 and heat to approximately 60C: The
liquid becomes somewhat yellow and the evolution of gas at the tin goes a
little faster again.
Allow to stand for a while and let cool down: The evolution of gas becomes very
slow again. The liquid remains clear and light yellow.
Remark:
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From this experiment one can conclude that tin can be dissolved in acids, but
the reaction is very slow. Even in aqua regia, the element dissolves very
slowly.