Flame reaction is strictly platinum wire, inert metal, not easy to react with other substances, and high melting point. The reaction in which certain metals or their compounds are chemically burned in a colorless flame to give the characteristic color of the flame is called flame reaction. Flame reaction is a very old qualitative analysis method.
The flame reaction is actually a physical change in the energy levels of the electrons inside the atoms of matter. Generally speaking, flame reactions are changes in the energy of electrons in atoms, and do not involve changes in the structure or chemical properties of substances. Some metals or their compounds give the flame a special color when it burns because the atoms of these metals jump from lower to higher energy orbitals when they receive the energy from the flame. But electrons in higher energy orbitals are unstable and jump quickly back into lower ones, releasing excess energy as light. Because the atoms of different elements have different structures, the energy of electrons during the transition changes differently, so they emit different wavelengths of light. If the wavelength of the light emitted is within the range of visible light, the characteristic color of the element will be observed in the flame. The special flame color we see from the experiment of flame color reaction is the color of spectral line. The spectrum of each element has some characteristic line, which releases characteristic color and makes the flame color. According to the flame color, the existence of a certain element can be judged. For example, magenta flame color contains strontium, green flame color contains copper, yellow flame color contains sodium, purple flame color (through blue cobalt glass) contains potassium and so on.
This property of elements can be used in chemical experiments to test the presence of some metals or metal compounds, which is the flame reaction in material testing. In flame reaction, platinum wire welded to the glass rod is burned by flame outside the alcohol lamp until it is the same color as the original flame. After that, the platinum wire is dipped in the solution and continued to burn on the external flame to observe the color of the flame. When using again, platinum wire should be washed with hydrochloric acid first, and then dipped in another solution when burning colorless on the external flame. If the material is limited, pure iron wire can be used instead of platinum wire, because the flame reaction of iron wire is colorless.
