Question

Is Na + HCl = H2 + NaCl a double displacement reaction??

Answer 1

No, it is a single displacement reaction.

Explanation:

No.

Double displacement reactions have the general formula of `AB+CD->AD+CB`. Where each letter is either an element or polyatomic ion.

Single displacement reactions have the general formula of `X+YZ->Y+XZ` - in which the cation displaces another cation/hydrogen, OR `X+YZ->Z+YZ` - in which an anion displaces another anion. Each letter is either an element or polyatomic ion.

Single displacement reactions are typically based off of the activity series:

A cation `(A)` can only displace another cation `(B)` if `(A)` is higher than `(B)` on the series. This is all based off of ionic bonds, in which electrons are transferred.

Here, we see sodium is much higher than hydrogen, therefore we can conclude a reaction occurs. In addition, only 3 elements (no polyatomic ions so I won't talk about it) are presented, indicating a single displacement reaction. A double displacement reaction typically has 4 elements (again, not including polyatomic ions).

Hope this helps :)