Question

What gas is formed when magnesium and hydrochloric acid are combined?

Answer 1

The gas formed is hydrogen gas `("H"_2")`.

Explanation:

The chemical reaction between `"Mg"` and `"HCl"` is:

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

As you can see, the gas that is formed is hydrogen.

Answer 2

Hydrogen gas

Explanation:

We got magnesium (a metal) and hydrochloric acid (an acid). The general word equation for that reaction is:

`"acid + metal" \ -> \ "salt + hydrogen gas"`

And so here, we get:

`Mg(s)+2HCl(aq)->MgCl_2(aq)+H_2(g)uarr`

So, hydrogen gas is formed and released. It can be tested by lighting a small splint which "pops" in contact with hydrogen gas.