Ruo (state)

The State of Ruò was a small vassal state during the Chinese Zhou Dynasty (1046–256 BCE) whose rulers used the title Zǐ (子), roughly equivalent to a Viscount. Located between the States of Qin and Chu, Ruo was eventually annexed by the State of Chu.

Rise and fall

Ruo’s capital was initially located at Shangmi (商密), also known as “Upper Ruo” (上鄀). In 635 BCE, the State of Qin and its equally powerful ally the State of Jin attacked Ruo whereupon the neighboring State of Chu, also an enemy of Qin and Jin, came to its aid. The people of Shangmi surrendered to Qin whilst the commander of the Chu army was captured. Thereafter the Qin army returned to their territory with the Chu pursuit of their troops coming too late. By 622 BCE, Ruo’s relations with Qin had become closer but they still wavered over the question of their relations with Chu. This led to Qin capturing Ruo and incorporating the city into their own territory. Ruo moved their capital into neighboring Hubei Province, close to the city of Yicheng whereupon it became known as “Lower Ruo” (鄀下). After the move, Ruo became a vassal state of Chu and at an unknown date fully assimilated into the state.

Ruthenium(IV) oxide

Ruthenium(IV) oxide is the inorganic compound with the formula RuO₂. This a black solid is the most common oxide of ruthenium. It is widely used as an electrocatalyst for producing chlorine, chlorine oxides, and O₂ catalyst is ruthenium(IV) oxide. Like many dioxides, RuO₂ adopts the rutile structure.

Preparation

It is usually prepared by oxidation of ruthenium trichloride. Nearly stoichiometric single crystals of RuO₂ can be obtained by chemical vapor transport.

Films of RuO₂ can be prepared by chemical vapor deposition (CVD) from volatile ruthenium compounds. RuO₂ can also be prepared through electroplating from a solution of ruthenium trichloride.

Uses

Ruthenium (IV) oxide is being used as the main component in the catalyst of the Sumitomo-Deacon process which produces chlorine by the oxidation of hydrogen chloride.

RuO₂ can be used as catalyst in many other situations. Noteworthy reactions are the Fischer-Tropsch process, Haber-Bosch process, and various manifestations of fuel cells.