Šis jautājums mani mulsināja ķīmijas stundās, bet paskaidrot tā arī neviens nepacentās.

Kāpēc karaļūdens (slāpekļskābes un sālsskābes maisījums) spēj šķīdināt zeltu, ja atsevišķi to nedara?

Nu re. Pavisam nejauši atradās atbilde.

Aqua regia works to dissolve gold, even though neither constituent acid will do so alone because, in combination, each acid performs a different task. Nitric acid is a powerful oxidizer, which will actually dissolve a tiny (virtually undetectable) amount of gold, forming gold ions. The hydrochloric acid provides a ready supply of chloride ions, which react with the latter, thus taking the gold out of the solution. This allows further oxidation of gold to take place, and so the gold is dissolved.