At room temperature, platinum does not react with minerals and organic acids, but under heating, sulfuric acid can make platinum dissolve slowly or completely in aqua regia.
At high temperature, carbon can be dissolved in platinum, and its solubility increases with the increase of temperature. When the temperature drops, carbon will precipitate from platinum, but this will make the performance of platinum brittle, which is called poisoning. Therefore, a carbon crucible cannot be used when dissolving platinum.
Compared with similar elements, gold is chemically stable. Ionization potential of gold is very high; Therefore, at high temperature, gold can be dissolved in mixed acids such as chlorine, thiourea, selenic acid, telluric acid and sulfuric acid.
The chemical stability of silver is worse than that of gold. Chen Fang will gradually form a black film on its surface at room temperature. When heated, silver reacts with chemicals more easily; At high temperature, silver ions are extremely active, and it is easy to produce metal splashing to form "silver rain" phenomenon.
The standard electrode potential of copper is higher than that of hydrogen, so copper has good chemical stability in many media. When the annealing temperature is too high, a coarse grain structure appears, which reduces the strength of copper. Pure copper contains brittleness, and when some impurity elements are involved, copper will appear "cold brittleness" during cold transformation.
Gypsum is red at high temperature.