揮発

• Reading: きはつ
• Romaji: kihatsu
• Kanji breakdown: 揮 (ki) — to emit, to brandish; 発 (hatsu) — to discharge, to emit
• Pronunciation: /ki.ha.tsɯ/

Meaning

Volatilisation; evaporation. The process by which a substance changes from liquid or solid phase to vapour at relatively low temperatures.

A chemistry and materials science term describing the tendency of a substance to escape into the gas phase. 揮発性 (volatility) is a key property: 揮発性有機化合物 (VOC — volatile organic compounds) are a major environmental and public health concern. 揮発油 (volatile oil, gasoline) is an older term for petrol/gasoline. High volatility means a substance evaporates readily at room temperature. The opposite tendency is described as 不揮発性 (non-volatile). The verb form is 揮発する.

Examples

1. エタノールはアルコールの中でも特に揮発性が高く、常温で急速に蒸発する。 Ethanol is particularly highly volatile among alcohols, and evaporates rapidly at room temperature.
2. 塗料に含まれる揮発性有機化合物は、換気の悪い室内で健康被害を引き起こすことがある。 Volatile organic compounds contained in paint can cause health problems in poorly ventilated indoor spaces.
3. その化合物は揮発しやすいため、密閉容器に保存する必要がある。 Because the compound volatilises easily, it must be stored in a sealed container.

Usage Guide

Context: chemistry, materials science, environmental science, occupational health

Tone: technical, academic

Origin & History

Sino-Japanese compound: 揮 (ki) — to brandish, to emit + 発 (hatsu) — to discharge, to emit. The character 揮 carries a sense of releasing or dispersing outward. Used in Japanese chemistry since the Meiji era to translate the concept of 'volatility' and 'volatilisation'.

Cultural Context

Era: Meiji-Modern

Generation: Adult

Social background: Educated