Final answer:
To calculate a net ionic equation, follow the steps of writing and balancing a molecular equation, writing an ionic equation, and then eliminating spectator ions to obtain the net ionic equation. The net ionic equation shows only the elements, compounds, and ions directly involved in the chemical reaction.
Step-by-step explanation:
To calculate a net ionic equation, you need to follow a step-by-step process. First, write and balance the molecular equation. Then, write the ionic equation by separating the soluble reactants and products into their respective cations and anions. Carry through any coefficients. Finally, eliminate spectator ions to obtain the net ionic equation, which shows only the elements, compounds, and ions directly involved in the chemical reaction.
For example, when copper (II) chloride and potassium phosphate react, a precipitate of copper (II) phosphate is formed. The balanced net ionic equation for this reaction is: Cu^2+ (aq) + PO4^3- (aq) → Cu3(PO4)2(s).
It is important to note that net ionic equations must be balanced by both mass and charge. Balancing by mass ensures equal masses of each element on both sides of the equation, while balancing by charge ensures the overall charge is the same on both sides. If the molecular equation is properly balanced, the net ionic equation will be balanced by both mass and charge.