Quick way to oxidize copper with household chemicals?

Visually: Copper is brownish-red, like a penny. Brass is a golden color.

Oxidizing: Copper will oxidize more easily than brass. Copper oxides are green or blue, and brass oxides are black. Add a bit of acid--vinegar or lemon juice are acidic household chemicals. At first it may get shinier. Oxidation can be hastened by using hydrogen peroxide (found in a brown bottle at the drugstore) in addition to the acid.

RE:

Quick way to oxidize copper with household chemicals?

I have a piece of metal here and I'm not sure if it's copper or brass, but I need to find out. I figure the easiest way to find out is to oxidize some of it and see if it turns green, correct? Could anyone give me a method that will oxidize copper relatively quickly?

How To Oxidize Copper

Brass is mostly copper combined with zinc. Both copper metal and brass form a patina. The green patina of copper is actually a mixture of several compounds including CuCl2, CuSO4, CuCO3 and CuO. Copper(II) oxide is blue, but forms very small particles, and so copper(II) oxide often appears black. Brass may also form a green patina.

The patina idea, while interesting is not the easiest, nor the best way to distinguish brass from pure copper. A better test is to compare the densities of the two metals. You can determine the volumes by liquid displacement and measure the masses with a balance. Compute the density with D=m/V.

The density of copper is 8.94 grams per cubic centimeter, and the density of brass (depending on the composition of the mixture) is 8.4 to 8.7 grams per cubic centimeter.

Bleach will oxidize it. Brass will oxidize, just not as much as copper, so unless you have a comparison sample, this won't be a great test.

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Most of these wires are too fine and small to solder. You may be better off twisting them together. Check Radio Shack for wire splicing stuff, like crimp on connectors.