Copper – one of the most valuable elements of the Table of Mendeleyev used by the person. Appearance – plastic metal, golden-pinkish color. It is widespread in the nature in the form of connections, but also nuggets meet. The most part goes for production of electric wires and heat-exchanging pipes, thanks to its exclusively high electro- and heat conductivity and also malleability, plasticity. Copper - low-active metal, but enters chemical reactions including it is oxidized.
It is required to you
- - piece of a thin copper wire;
- - "handle";
- - flame source, for example, spirit-lamp or gas burner.
Instruction
1. Some people had to see bronze monuments which literally painted in light-green color. It is not work of unknown vandals at all as can seem at first sight - it was oxidation reaction. Remember that bronze – copper alloy with tin. A monument, being under the open sky, is affected by precipitation. And the fair amount of oxygen and carbon dioxide is airborne. There is also a chemical reaction: 2Cu + H2O + CO2 + O2 = Cu2CO3(OH)2. The formed green substance is a malachite! That, sung by the storyteller Bazhov. Old bronze monuments are obliged to it by the coloring.
2. It is easily possible to guess that than the climate and the more is more damp than industrial and automobile exhausts, the copper which is contained in bronze will be oxidized quicker. It is also possible to make very simple and evident experiment on copper oxidation.
3. Strong clamp a wire "handle" (a wooden clothespeg or passatizha) and bring the free end in a flame of a spirit-lamp or a torch. Take so some time that the wire was well calcinated. After that take out from fire. You will distinctly see that the cooled-down wire changed color, that is became black. It was oxidation reaction which looks as follows: 2Cu + O2 = 2CuO.
4. It is possible to continue experience, having placed the "black" end of a wire in a test tube with the diluted hydrochloric acid. On your eyes the wire will accept the color inherent in pure copper again, and solution of acid will become light blue because there was a copper oxide restoration to formation of its soluble chloride. Chemical reaction at the same time will look so: SuO + 2HCl = CuCl2 + H2O.