Which one of the following was the first mineral acid discovered?
- (a)Sulphuric acid
- (b)Hydrochloric acid
- (c)Nitric acid
- (d)Phosphoric acid
Correct — C, Nitric acid. Among the mineral (inorganic) acids, nitric acid — known to early alchemists as aqua fortis, or 'strong water' — is conventionally regarded as the first to be discovered and described, in the medieval alchemical literature (the account in Pseudo-Geber, after about 1300). Sulphuric, hydrochloric and phosphoric acids were clearly characterised later.
- (a)Sulphuric acid — A very important mineral acid ('oil of vitriol'), but its clear characterisation came after nitric acid; it is not regarded as the first discovered.
- (b)Hydrochloric acid — Muriatic acid was described later than nitric acid, and was often produced together with it to make aqua regia.
- (d)Phosphoric acid — A comparatively later discovery, following the isolation of phosphorus in the 17th century; it is not the first mineral acid.
Mineral acids are inorganic acids such as nitric, sulphuric, hydrochloric and phosphoric acid, as distinct from organic acids like acetic acid. They were first prepared and described by medieval alchemists. Nitric acid, or aqua fortis, is conventionally taken to be the earliest of these to be discovered.
The likely trap is sulphuric acid, often called the 'king of chemicals' because of its industrial importance — but importance is not the same as being discovered first, and the conventional answer for the first mineral acid is nitric acid. Historical dating of these discoveries is genuinely uncertain, yet nitric acid remains the standard textbook and exam answer.
- Mineral acids are inorganic acids such as nitric, sulphuric, hydrochloric and phosphoric acid.
- Nitric acid (aqua fortis) is conventionally described as the first mineral acid discovered, in medieval alchemy (the account in Pseudo-Geber, c. 1300).
- A mixture of nitric and hydrochloric acid is aqua regia, which can dissolve gold and platinum.
- Scholarly dating of these discoveries is uncertain and debated, but nitric acid is the accepted exam answer.
- Aqua fortis (Nitric acid) — described in medieval alchemy (Pseudo-Geber, c. 1300): conventionally the FIRST mineral acid
- Oil of vitriol (Sulphuric acid) — characterised by later alchemists
- Muriatic acid (Hydrochloric acid) — described later; combined with nitric acid to make aqua regia
- Phosphoric acid — later still, after phosphorus was isolated (17th century)
Nitric acid (aqua fortis) is conventionally taken as the first mineral acid discovered — option (c).
- Assuming sulphuric acid ('king of chemicals') was discovered first — nitric acid is the conventional answer.
- Confusing 'most important or most used' (sulphuric acid) with 'first discovered' (nitric acid).
A history-of-chemistry GK item — 'the first mineral acid discovered' points to nitric acid (aqua fortis).
No directly related past PYQ was found.
- practice — not a real PYQ
The old alchemical name 'aqua fortis' refers to
- (a)sulphuric acid
- (b)hydrochloric acid
- (c)nitric acid
- (d)acetic acid
Answer(c) nitric acid.
- practice — not a real PYQ
A mixture of concentrated nitric acid and hydrochloric acid that can dissolve gold is called
- (a)aqua fortis
- (b)aqua regia
- (c)oil of vitriol
- (d)milk of lime
Answer(b) aqua regia.