Question

Write a balanced equation for the precipitation reaction that was used to separate Ba2+ from Ca2+ and Mg2+.

Answer 1

Answer:

${\rm Ba^{2+}} \, (aq) + {\rm {SO_4}^{2-}}\, (aq) \to {\rm BaSO_{4}}\, (s)$.

Explanation:

Make use of the fact that calcium sulfate ${\rm CaSO_{4}}$ and magnesium sulfate ${\rm MgSO_{4}}$ are much more soluble in water than barium sulfate ${\rm BaSO_{4}}$.

When sulfate ions ${\rm {SO_{4}}^{2-}}$ are added to dilute solutions containing ${\rm Ba^{2+}}\, (aq)$, ${\rm Ca^{2+}}\, (aq)$, and ${\rm Mg^{2+}}\, (aq)$, precipitation would be visible only in the solution with ${\rm Ba^{2+}}\, (aq)\!$. Barium sulfate would be the precipitate.

${\rm Ba^{2+}} \, (aq) + {\rm {SO_4}^{2-}}\, (aq) \to {\rm BaSO_{4}}\, (s)$.

This ionic equation is balanced as it conserves both the atoms and the charges on the ions.