Determination through chemical experiments
The reaction with concentrated nitric acid is indicative: if the latter is dropped onto the surface of a copper product, a green-blue color will occur.
A qualitative reaction to copper is dissolution in hydrochloric acid followed by exposure to ammonia. If a copper sample is left in an HCl solution until completely or partially dissolved, and then ordinary pharmaceutical ammonia is dropped into it, the solution will turn intensely blue.
Important: working with chemicals requires precautions. Independent experiments should be carried out in a well-ventilated area using personal protective equipment (rubber gloves, apron, goggles).
How to distinguish copper from other metals
For most of us, knowledge about copper and its properties is limited to a school chemistry course, which is quite enough at the everyday level. However, sometimes there is a need to reliably determine whether a material is a pure element, an alloy, or even a composite material. The opinion that this information is needed only by those who are engaged in the acceptance or delivery of scrap metal is erroneous: for example, on amateur radio forums, topics are often raised about how to distinguish copper in wires from copper-plated aluminum.
Briefly about element No. 29
Pure copper (Cu) is a golden-pink metal with high ductility, thermal and electrical conductivity. Chemical inertness in an ordinary non-aggressive environment is ensured by a thin oxide film, which gives the metal an intense reddish tint.
The main difference between copper and other metals is color.
. In fact, there are not so many colored metals: only gold, cesium and osmium are similar in appearance, and all elements included in the group of non-ferrous metals (iron, tin, lead, aluminum, zinc, magnesium and nickel) have a gray color with varying intensity of shine.
An absolute guarantee of the chemical composition of any material can be obtained only through spectral analysis. The equipment for carrying it out is very expensive, and even many expert laboratories can only dream of it. However, there are many ways to distinguish copper at home.
with a high degree of probability.
Is copper magnetic?
My daughter just loves magnets! At some point, her love for them became simply enormous. She could spend 20 minutes rearranging the souvenir magnets on our refrigerator. I decided that if I did it this way it would be useful. And I bought her a bunch of cheap children’s magnets from Drofa-Media
Paramagnets and ferromagnets
Let's consider the option when each atom of a substance has its own magnetic field. These fields are multidirectional and compensate each other. If you place a magnet next to such a substance, the fields will be oriented in one direction. The substance will have a magnetic field, a positive and a negative pole. Then the substance will be attracted to the magnet and can itself become magnetized, that is, it will attract other metal objects. For example, you can magnetize steel clips at home. Each one will have a negative and a positive pole, and you can even hang a whole chain of paper clips on a magnet. Such substances are called paramagnetic.
Ferromagnets are a small group of substances that are attracted to magnets and are easily magnetized even in a weak field.
Numerical experiment
And now there will be something for which all this was started. They brought up a theory here, you know. What is she capable of? What if it’s just like a shadow on a fence? Or it doesn't work at all...
Let's start again with the magnet. I found it on online shopping sites. NdFeB magnets for sale, remanent magnetization
Gs. However, this does not mean that the field directly next to the magnet is as large. Once upon a time it was possible to measure with a device. The fields directly on the surface of such magnets are usually smaller and amount to 4000 - 5000 Gauss. And the mass of such a magnet will be approximately
G.
Our video is from MIT, therefore it is American. I’ll try to guess the dimensions of their demo setup in inches (they like to measure everything in inches). The size of the magnet is similar to
inches in diameter. This is one of those that are on sale. The length of the copper pipe is similar to
inches (1 ft), and the inside and outside diameters of the pipe are most likely
inches,
inches.
We seem to have figured out the geometry. Now the physical properties. Conductivity of copper
Sm/m. Well, I must admit that no matter how hard I tried, I could not find anything on the topic: how are the residual magnetization and the magnetic moment of a permanent magnet related. Therefore, keeping in mind the measurements that I once made, I simply selected this value
so that the field at the surface of the magnet is somewhere between 4500 and 5000 Gauss. Happened
A m². To make sure that the fields are similar to the real ones, I plotted the magnetic induction versus the radial coordinate at a distance of half a diameter from the center of the ball.
z-component of the magnetic field near the surface of a permanent magnet
Now let's use the solution to the equation of motion to plot the speed of the magnet. For all parameters selected above, the friction coefficient is equal to
N/(m/s), steady speed —
cm/s - just about 3 inches per second! In the video, the ball passes through a 12-inch long pipe in about 4 seconds.
THIS IS AWESOME!
I know that it is correct to write “test” through “e”, but in this case it would be more correct to write through “o”
