Now, a very common example is when two moles of hydrochloric acid in an Aqueous state react with 1 mol of magnesium solid. This produces 1 mol of Mg CL, two in the Aqueous state, and 1 mol of diatomic H two in a gas state. So this is a single display for reaction in which our Mg kicks off this H, forming our reactant, and this H combines with another H forming a diatomic gas. Now let's look at a double displacement or a metaphor reaction. Now, we have reactance A and B react with reactants CD. What happens now is our C displaces this B kicks off this B, forming a bond with a, and at the same time, this B kicks off this C, forming a bond with D. And what we get is the following.