Write the equation for reaction between magnesium and dilute hydrochloric acid

The reactants are magnesium (Mg) and dilute hydrochloric acid (HCl).

When a metal reacts with an acid, a salt and hydrogen gas are produced. The salt formed from magnesium and hydrochloric acid is magnesium chloride ($MgCl_2$).

$Mg + HCl \rightarrow MgCl_2 + H_2$

To balance the equation, we need to ensure the number of atoms of each element is the same on both sides.
We have 1 Mg on both sides.
We have 1 Cl on the left and 2 Cl on the right, so we need to put a coefficient of 2 in front of HCl.
$Mg + 2HCl \rightarrow MgCl_2 + H_2$
Now we have 2 H on the left and 2 H on the right.
The equation is now balanced.

The balanced equation for the reaction between magnesium and dilute hydrochloric acid is:
Mg + 2HCl \rightarrow MgCl_2 + H_2