2
$\begingroup$

There's an experiment I have no way of performing but want to know its results. The instructions (in short) are:

Dip a piece of copper in a glass of concentrated nitric acid, $\ce{HNO3}$, using a pincette. When a brown gas starts forming, take out the piece of copper and rinse it with water. Right after that dip it into $\ce{HgNO3}$ solution. Leave it in there for some time and then take it out of the solution. Rinse it with water and wipe it with a napkin.

How does the piece of copper look?

What I've worked out is that the first part can be written as: $$\ce{Cu (s) + 4HNO3 (aq) -> Cu(NO3)2 (aq) + 2NO2 (g) + 2H2O(l)}$$ and that $\ce{NO2}$ is the brown gas.

What I'm not sure about is why exactly I'm dipping the copper piece into a solution of $\ce{HgNO3}$ following the above reaction. And why am I rinsing it with water before dipping it into the $\ce{HgNO3}$ solution?

$\endgroup$
  • $\begingroup$ @student States of aggregation should not be subscripted, it is not wrong, but the recommendations (Sec. 2.1.) are different. $\endgroup$ – Martin - マーチン May 12 '16 at 5:30
  • $\begingroup$ @Martin-マーチン Thank you, will bear it in mind. $\endgroup$ – user25546 May 14 '16 at 7:22
1
$\begingroup$

Metals often have corrosion on their surface, such as oxides. By dipping in nitric acid and then rinsing with water you would achieve a true copper metal surface free of oxide or other corrosion products.

$\endgroup$
1
$\begingroup$

You will likely be creating a mercury-copper amalgam similar to this

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.