Question

What are the spectator ions in the equation `2Na^+(aq) + SO_4 ^(2-) (aq) + Ba^(2+)(aq) + 2Cl^(-)(aq) → BaSO_4(s) + 2Na^+(aq) + 2Cl^(-) (aq)`?

Answer 1

The spectator ions are the ones that can be cancelled out of the equation:

Explanation:

`Ba^(2+) + cancel(2Na^(+)) + SO_4^(2-) + cancel(2Cl^(-)) rarr BaSO_4(s) + cancel(2Cl^(-)) +cancel(2Na^(+))`

TO GIVE,

`Ba^(2+) + SO_4^(2-) rarr BaSO_4(s)darr`

Which is the `"net ionic equation."` The spectator ions are simply along for the ride and do not participate in macroscopic chemical change.

All I have done is subtract the common reagents from each side of the equation. We do the same sort of thing in algebra when we subtract something from BOTH sides of the equation.