Question

What is the difference between a double replacement and an acid-base reaction?

Answer 1

Although similar, neutralisation reactions do not displace the `H` and `OH` atoms, but rather react together to form water. This is not evident in double displacement reactions.

Explanation:

Generally speaking, a double displacement reaction has a formula of `AB+CD->AD+CB`. This normally occurs between two ionic compounds but is not restricted to it *needs confirmation.

An acid-base reaction is a neutralisation reaction in which the hydrogen and oxygen atoms within the acid and base yields water, while the other reactants form a salt.

This means that they don't displace each other, but rather forms a new compound.

Examples:

Double displacement

`BaCl_"​2" ​​ (aq)+Na_"2"SO_"4" ​​ (aq)→BaSO_"4" ​(s)+2NaCl (aq)`

You see that the `AB+CD->AD+CB` formula applies, where:
=> `A` refers to `Ba`.
=> `B` refers to `Cl`.
=> `C` refers to `Na`.
=> `D` refers to `SO_"4"`.

Neutralisation

`H_"2"SO_"4" + 2KOH -> K_"2"SO_"4" + 2H_"2"O`

As you can see, the `H` and `OH` atoms form water, while the other reactants (`K` and `SO_"4"`) form `K_"2"SO_"4"`.

Hope this helps :)