Hydroazoic acid - Ajikasuisosan

Japanese: アジ化水素酸 - あじかすいそさん

...It is highly soluble in water and ethyl alcohol. Its aqueous solution is called hydrazoic acid (formerly called triazoic acid) and acts as a weak acid. The dissociation constant K = 1.8 × 10 ^-5 (25°C).

From [Azide]

...For example, compounds such as NaN ₃ , KN ₃ , AgN ₃ , Hg(N ₃ ) ₂ , Pb(N ₃ ) ₂ , ClN ₃ , BrN ₃ , CH ₃ N ₃ , C ₆ H ₅ N ₃ , etc. The -N ₃ group has a linear N-N-N structure and is a pseudohalogen (a group that exhibits properties similar to halogen atoms), and an aqueous solution of hydrogen azide is called hydroazic acid, which is an acid similar to hydrohalic acid. Thus, azides are similar in many ways to halides. ...

*Some of the terminology explanations that mention "hydrazoic acid" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…水，エチルアルコールによく溶ける。水溶液はアジ化水素酸と呼ばれ(古くトリアゾ水素酸とも呼ばれた)，弱酸として働く。解離定数K＝1.8×10^－5(25℃)。…

【アジド】より

…たとえば，NaN₃,KN₃,AgN₃,Hg(N₃)₂,Pb(N₃)₂,ClN₃,BrN₃,CH₃N₃,C₆H₅N₃などのような化合物がそうである。－N₃基は直線型のN－N－Nのような構造をもち，プソイドハロゲン(ハロゲン原子に似た性質を示す基)の一つであり，アジ化水素の水溶液はアジ化水素酸というようにハロゲン化水素酸に似た酸である。したがってアジドも多くの点でハロゲン化物と似ている。…