Mercury oxide is an alkaline oxide with the chemical formula of HgO, which has two variants: red and yellow. Almost insoluble in water and ethanol, decomposed at 500℃. Toxic and irritating. Mercury oxide can be used to prepare other mercury compounds, and can also be used as catalysts, pigments, antibacterial agents and electrode materials for mercury batteries.
20 17,101The list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization on October 27th was preliminarily sorted out for reference. Mercury and inorganic mercury compounds are listed as three carcinogens.
Study history
As early as 2000 years ago, the book Shen Nong's Classic of Materia Medica compiled in Qin and Han Dynasties recorded the situation of mercury mines, calling them Cinnabar, cinnabar and mercury, and included them in the category of medicines.
It is found that if oxygen-containing substances are added to mercury, a mercury oxide powder compound will be formed, which is called "Sanxiandan". The medicinal value of Sanxiandan is described in detail in many ancient medical books, and alchemists also use mercury oxide as a common raw material.
In modern times, people have a deeper understanding of mercury oxide. 1774, British scientist priestley put mercury oxide on the surface of mercury in a glass bell jar and concentrated sunlight on it with a magnifying glass.
It was soon discovered that the mercury oxide decomposed, releasing a gas to squeeze out the mercury in the glass cover. He collected this gas by draining water and collecting gas, and then studied its properties.
Priestley lit the dry wood and put it in a glass bottle. It was found that the battens burned more vigorously and the flames were brighter. Therefore, oxygen is produced for the first time, and it is proved by experiments that oxygen has the properties of combustion-supporting and breathing.
1777, lavoisier discovered that oxygen and mercury can be obtained by heating mercury oxide, proved the law of mass conservation in chemical reaction through experiments, put forward the theory of combustion oxidation, overthrew the theory of phlogiston, and made modern chemistry flourish.
physicochemical property
Bright red or orange-red scaly crystals or crystalline powder.
When the powder is extremely fine, it is yellow, heavy and tasteless. But its color has nothing to do with its particle size. Soluble in dilute hydrochloric acid, dilute nitric acid, cyanide alkali and iodide alkali solution, slowly soluble in bromide alkali solution, almost insoluble in water and ethanol.
Under the action of light, it slowly turns dark black and toxic. When heated, when the temperature reaches 500℃, mercury oxide will become elemental mercury, and oxygen will be released when decomposed. If the heating temperature is lower than the decomposition temperature, the color will turn black, and it will return to its original color after cooling. Almost insoluble in water and ethanol, soluble in nitric acid and hydrochloric acid to form high mercury salt.
Mercury oxide can be used as an oxidant. When chlorine gas is introduced into the newly made mercury oxide, chlorine monoxide will be obtained. Mercury oxide reacts with hydrogen peroxide to produce mercury peroxide, which belongs to β -type orthorhombic system. Sulfur dioxide can be oxidized to sulfur trioxide, arsenic trioxide can be oxidized to arsenic pentoxide and phosphorous acid in water can be oxidized to phosphoric acid.
structure
The particle sizes of red mercury oxide and yellow mercury oxide are different. The particle size of yellow mercuric oxide is generally below 2μm, and most of red mercuric oxide is10 ~ 20 μ m. Red mercuric oxide can be converted into yellow mercuric oxide after being crushed.
These two variants are orthogonal crystal systems with infinite chain structure in the same plane, and each mercury atom is almost linearly connected to two oxygen atoms around it, and coordinates with four oxygen atoms on adjacent chains at the same time. ∠O-Hg-O is 179∠Hg-O-Hg is 107.
Hexagonal mercury oxide can be obtained by the reaction of dilute solution of K2HgI4 with alkali. The structure is similar to orthogonal mercuric oxide, but the chains are not in the same plane, but wound in a spiral shape.
use
Mercury oxide can be used as oxidant, organic reaction catalyst, analytical reagent and electrode.