Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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sodium fluoride : NaF
hydrochloric acid : HCl
iron : Fe
Class:
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elem=Fe,F
redox
Summary:
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Iron does not dissolve quickly in dilute hydrochloric acid. When some sodium
fluoride is added, then it still does not dissolve quickly. This is in strong
contrast with titanium metal, which does dissolve quickly in dilute HCl,
when some HF is present.
Description:
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Add some iron metal to dilute hydrochloric acid (appr. 10% HCl by weight): The
iron does not dissolve quickly. No visible changes, at least not within several
minutes.
Add a spatula of NaF: The solid dissolves, the iron metal is not attacked at a
higher rate after adding the NaF. Apparently, HF is not capable of attacking
iron metal at an appreciable rate nor does it change the speed with which
dilute HCl attacks the metal. This is in marked contrast with titanium. When
the same experiment is done with titanium, then one can see a strong increase
of the speed with which the metal dissolves.