[Mexer]

I've recently made a fun little reaction between a copper coin and some HNO3 . I put the HNO3 in a bottle cap outside my window (I'm at ground level floor in my flat). So what it did was Cu + HNO3 -> Cu(NO3)2 + NO + H2O which resulted in a orange looking liquid that dripped down my window (thing where you put flowers n stuff) and went on the white wall outside. What it did was it stained the wall like crap with that color and I can't remove it with water or house detergent ...I think the Cu(NO3)2 is the one that's the problem...

Can you please suggest me a quick solution to remove that ugly stain?

Would a photo of the wall help you?

[Borek]

Copper would be bluish or greenish, if it is orange, it is something else.

What was the bottle cap made of?

[Mexer]

plastic...

[Arkcon]

Nitric acid "stains" many things  -- fingers for example.  Its not a stain, but a reaction with a colored product.  You can wait for it to wear off, if possible, but you may have to repaint, or replace, that portion of wall.  If you are not the owner of this wall, you can take this a chance to learn something ... nitric acid, of sufficient strength to attack copper, must stay in a laboratory, not your house.  Your window box was not far enough away to be safe from accidents.  You should have done your experiment maybe 5 ft away, on an old rotted wet tree stump, or better, bare earth.  Stone, metal, grass are examples of things that people care about, just like walls, and you have to treat those things with care.

[Mexer]

Nitric acid "stains" many things  -- fingers for example.  Its not a stain, but a reaction with a colored product.  You can wait for it to wear off, if possible, but you may have to repaint, or replace, that portion of wall.  If you are not the owner of this wall, you can take this a chance to learn something ... nitric acid, of sufficient strength to attack copper, must stay in a laboratory, not your house.  Your window box was not far enough away to be safe from accidents.  You should have done your experiment maybe 5 ft away, on an old rotted wet tree stump, or better, bare earth.  Stone, metal, grass are examples of things that people care about, just like walls, and you have to treat those things with care.

Thanks! how long should I wait for it to go off; does it really? It's not a regular wall paint, pics of the stains: http://imgur.com/a/Qy6eX

[Arkcon]

That looks to me like stone, or stucco.  The wall was likely at least slightly attacked by the acid.  That's a little odd, considering you imply you had a tiny amount in a cap.  Maybe the wall effect is just dirty from soil overflowing you window box.  Or maybe you want to claim that's the case, if anyone asks.

[billnotgatez]

Here is a possible solution.
I am assuming that the window box for plants is above the stain.
Purchase some plants that have long hanging stems like ivy or spider plant that are already grown enough to cover the stains. Plant them in the flower box hanging over the part that is stained. Over time the stain may fade while hidden under the plants. Of course over time the plant may add to the color of the wall, but that would be expected.

[Mexer]

I think I'll just buy some paint and paint it back. Thanks for the silly solution though   (i don't have or dont usually put plants on my window base)

[billnotgatez]

 

you may end up painting the whole wall to make it look alike

good luck