Chemical Equations: Understanding Total Ionic Equation
What is the total ionic equation for the following reaction? H2CrO4 + Ba(OH)2 → H2CrO4- + 2OH- → CrO4- + 2H2O
Which option provides the correct total ionic equation for the reaction?
The Answer is
The answer is the third option which is the most complex one.
Taking into account the definition of total ionic equation, the total ionic equation in separated aqueous solution will be:
2 H⁺ + CrO₄⁻ + Ba²⁺ + 2 OH⁻ → Ba²⁺ + CrO₄⁻ + 2 H₂O
Ionic equation
The net ionic equation is a chemical equation for a reaction that lists only the species that participate in the reaction.
In other words, an ionic equation is a chemical equation where electrolytes in aqueous solution are written as dissociated ions. Usually this is a salt dissolved in water, where the ionic species are followed by (aq) in the equation, to indicate that they are in aqueous solution.
This Case
The balanced equation will be:
H₂CrO₄ + Ba(OH)₂ → BaCrO₄ + 2 H₂O
Taking into account that:
- Most hydroxides are poorly soluble, except those of alkali metals, such as Barium (Ba).
- All salts of CO₃²⁻, O²⁻, S²⁻, OH⁻, PO₄³⁻, CrO₄²⁻, Cr₂O₇²⁻, and SO₃²⁻ are insoluble (with exceptions).
- Strong electrolytes easily dissociate into their corresponding ions. H₂CrO₄ is a strong acid, therefore, it will dissociate into ions.
The total ionic equation in separated aqueous solution will be:
2 H⁺ + CrO₄⁻ + Ba²⁺ + 2 OH⁻ → Ba²⁺ + CrO₄⁻ + 2 H₂O