Mercury sulfide

Japanese: 硫化水銀 - りゅうかすいぎん（英語表記）mercury sulfide

Mercury sulfides include compounds of monovalent and divalent mercury.

(1) Mercury sulfide (I) When mercury chloride (I) Hg ₂ Cl ₂ is reacted with hydrogen sulfide at temperatures below -10°C, it becomes a black, unstable powder. Its chemical formula is Hg ₂ S and its formula weight is 433.2. In an aqueous solution at room temperature, it immediately disproportionates to
Hg ₂ ²⁺ +H ₂ S→Hg+HgS+2H ⁺
It can be decomposed as follows.

(2) Mercury(II) sulfide exists in two forms: the stable α (alpha) form, which is red, and the metastable β (beta) form, which is black. The chemical formula is HgS and the formula mass is 232.7.

[Nakahara Katsunori]

Red mercury sulfide

It occurs naturally as cinnabar, and is called vermilion when used as a pigment. It can be obtained by heating mercury with an aqueous solution of potassium pentasulfide ( _K2S5 ₎ , or by sublimating black mercury sulfide. Vermilion red crystalline powder (hexagonal crystal system). Hardness 2-2.5. Sublimes at 580°C. Gradually darkens in air. Insoluble in water and acid. Slightly soluble in aqueous solutions of alkali sulfides and alkali hydroxides. Soluble in aqua regia. In addition to being used as a pigment, it is used as an ointment to treat skin diseases.

[Nakahara Katsunori]

Black mercury sulfide

It can also occur naturally as black cinnabar. It is prepared by precipitating hydrogen sulfide into an aqueous solution of mercury(II) salt. It is a black powder (cubic crystal system). It sublimes at 446°C. It is insoluble in water and acid. It dissolves in an aqueous solution of alkali sulfide to form a thiosalt. It also dissolves in an aqueous solution of alkali hydroxide, and is easily soluble in aqua regia.

[Nakahara Katsunori]

[Reference] | Red

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

水銀の硫化物で、一価および二価水銀の化合物が知られている。

(1)硫化水銀(Ⅰ)　塩化水銀(Ⅰ)Hg₂Cl₂に－10℃以下で硫化水素を作用させると黒色、不安定な粉末として得られる。化学式Hg₂S、式量433.2。常温の水溶液ではただちに不均化して、
　　Hg₂²⁺＋H₂S→Hg＋HgS＋2H⁺
のように分解する。

(2)硫化水銀(Ⅱ)　赤色の安定なα(アルファ)態と黒色の準安定なβ(ベータ)態との二つが存在する。化学式HgS、式量232.7。

［中原勝儼］

赤色硫化水銀

天然に辰砂(しんしゃ)として産し、顔料として用いられるときは朱(しゅ)という。水銀を五硫化カリウムK₂S₅水溶液と熱するか、黒色硫化水銀を昇華すると得られる。朱赤色結晶性粉末（六方晶系）。硬さ2～2.5。580℃で昇華する。空気中では徐々に暗色となる。水、酸に不溶。硫化アルカリ、水酸化アルカリ水溶液に難溶。王水に溶ける。顔料のほか軟膏(なんこう)として皮膚病の治療に用いられる。

［中原勝儼］