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

2 Answers
Nov 26, 2017

Answer:

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.

Nov 26, 2017

Answer:

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.