Precious metals

In the medieval people tried to create gold from all sorts of other materials. They believed that the "philosophers stone" could do these transmutations. Today we now that this is without nuclear transformation impossible and the nuclear transformation would be much more expensive than the gold (or any other valuable material that could be generated by it) would be worth.

Nevertheless there is a nice experiment which allows you to coat one metal with another so that a simple paper clip gets a golden (well, in fact it is copper) shine.

	Be careful not to bring the vinegar in contact with your eyes. Very young scientists should do this experiment together with their parents.
	Vinegar can cause stains on your clothes.

Materials you need for this experiment:

paper clip	The paper clip you will coat with coper.
vinegar	Vinegar is needed to enable the reaction.
5 cent (€) coin or any other copper coin	The copper ions will move in the vinegar the the less precious aluminium of the paper clip.
glas jar	The glas jar is needed to put all the stuff in it.

How to do the experiment:

	In the beginning your paper clip looks silvery due to the aluminum from which it is made of and the copper coin might even be a bit corroded. After all copper is no precious metal like gold, so it is very likely to corrode.
	Put the paper clip and the copper coin side by side into a glass jar and cover it with vinegar.
	Then you have to wait ... and wait ... and wait. A first indication will be that the copper coin becomes a bit more shiny since the copperoxide is dissolving in the vinegar.
	Unfortunately this process is very slow but after a few days you see that the color of the paper clip becomes more and more similar to the color of the copper coin.
	If you have a lot of patience, the paper clip will have the same color as the copper coin. You have covered the aluminum of the paper clip with a very thin layer of copper.

Be aware that always the more precious metal (copper) will cover the less precious metal (aluminum or iron). It never goes in the other direction. You might also have heard that higher temperature can increase the speed of such reactions. That is true but hot vinegar is creating vapors that you must not inhale! So don't try to make the experiment quicker by heating everything up. In this case it is really not a good idea!

Try to experiment with some other metals as well. What can you achieve? Have fun experimenting!