Question

Why is hydrochloric acid used in the laboratory in preference to nitric or sulfuric acids?

Answer 1

Because when it reacts rapidly with `"Mg"`, it forms `"H"_2` in the form of bubbles.

Explanation:

The chemical equation used in most cases to show formation of `"H"_2` is:

`"Mg"(s) + 2"HCl"(aq) -> "MgCl"_2(aq) + "H"_2(g)`

The hydrogen can be detected either by observing the small `"H"_2` bubbles in the solution or by holding a burning match or a lighter above the liquid container and watch the `"H"_2` burn with a small 'boom' sound.

Answer 2

Why? Well probably for convenience....

Explanation:

`HCl(aq)` is available as the concentrated acid....`[HCl]=10.6*mol*L^-1`, so-called `"muriatic acid"`, `"spirits of salt"`; bricklayers also use this stuff to wash the mortar off their brickwork.

We can conveniently add acid to water to dilute the concentrated acid (but never the reverse 'cos `"if you spit in acid it spits back"`).

Both dilute and concentrated acids can be handled with appropriate care and precautions in the lab (which are?)...and the reaction with a metal generates dihydrogen gas....

`Fe(s) + 2HCl(aq) rarr FeCl_2(aq) + H_2(g)uarr`

On the other hand, `"sulfuric acid"` is a NON-OXIDIZING acid, and `"nitric acid"`, the other common mineral acid, can generate poisonous and noxious `NO_2` upon reduction.