Question

What properties would have caused early researchers to name hydrogen "inflammable air"?

Answer 1

Dihydrogen is colourless, odourless, and tasteless. How do we characterize it? How do we even know it is there?

Explanation:

The action of an acid on a metal usually produces such a gas:

`M(s) + 2HX(aq) rarr MX_2(aq) + H_2(g)uarr`

The gas formed could be collected under certain circumstances. Its major distinguishing property was the reaction the gas underwent when a glowing splint was introduced to the vessel. The result? An audible whoosh-bang, and later careful researchers might have noticed the formation of water (and hence called this gas hydrogen, literally "water-forming").

So, the earliest researchers knew that the substance was a gas, but it was a gas unlike the air they breathed. Hence the name "inflammable air".