Question

When solutions of barium chloride (aq) and sodium sulfate (aq) are mixed, what is/are the spectator ion(s)?

Answer 1

`"Sodium and chloride ions........."`

Explanation:

We write the equation for the formation of `BaSO_4(s)` as:

`BaCl_2(aq) + Na_2SO_4(aq) rarr BaSO_4(s)darr + 2NaCl(aq)`

Alternatively, we could write the net ionic equation:

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

In other words, the `Na^+`, and `Cl^-` ions are along for the ride. The are passengers, spectators, and play no part in the macroscopic reaction.