Write the molecular, total ionic, and net ionic equations for the following reactions: (a) \(\mathrm{Ca}(\mathrm{OH})_{2}(a q)+\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q) \rightarrow\) (b) \(\mathrm{H}_{3} \mathrm{PO}_{4}(a q)+\mathrm{CaCl}_{2}(a q) \rightarrow\)

Molecular equations provide a straightforward representation of chemical reactions. In this type of equation, compounds are expressed as if they are not dissociated into ions, even when they are soluble in water. This format is useful for understanding the overall process.

For example, the balanced molecular equation for the reaction of calcium hydroxide and acetic acid is as follows: \[\begin{equation}\mathrm{Ca(OH)_2} + 2\mathrm{HC_2H_3O_2} \rightarrow \mathrm{Ca(C_2H_3O_2)_2} + 2\mathrm{H_2O}\end{equation}\]
The reactants, calcium hydroxide and acetic acid, interact to form products, which are water and calcium acetate. It's essential to ensure that the equation is balanced, meaning the number of atoms for each element is equal on both sides of the equation.

Total ionic equations show all the soluble ionic substances dissociated into ions. This form is more detailed than the molecular equation, as it represents the actual species present in the solution.

For instance, the total ionic equation for the same reaction would be: \[\begin{equation}\mathrm{Ca^{2+}} + 2\mathrm{OH^-} + 2\mathrm{H^+} + 2\mathrm{C_2H_3O_2^-} \rightarrow \mathrm{Ca^{2+}} + 2\mathrm{C_2H_3O_2^-} + 2\mathrm{H_2O}\end{equation}\]
This equation shows how calcium and hydroxide ions from calcium hydroxide react with hydrogen and acetate ions from acetic acid to form water and remain calcium acetate ions in solution.

Net ionic equations show the chemical species that are actually involved in the reaction, omitting the spectator ions. These equations highlight the essence of chemical reactions by focusing on the ions and molecules that change during the process.

For the given example: \[\begin{equation}2\mathrm{OH^-} + 2\mathrm{H^+} \rightarrow 2\mathrm{H_2O}\end{equation}\]
The hydroxide ions react with hydrogen ions to produce water, and this equation strips away the complexity to exhibit the core components of the reaction.

Spectator ions are present in the solution but do not actively participate in the chemical reaction. They retain their form and do not undergo a chemical change. Spectator ions help maintain electrical neutrality in solution, but they are not included in the net ionic equation because they do not contribute to the reaction.

For instance, in the case of the calcium hydroxide and acetic acid reaction, calcium and acetate ions are present but do not change their oxidation state or form any new compounds, so they are considered spectator ions.

Balancing chemical reactions is crucial to adhere to the Law of Conservation of Mass, which dictates that mass is neither created nor destroyed in a chemical reaction. This means you must ensure that the number of atoms for each element is the same on both sides of the chemical equation.

Whether you're writing molecular, total ionic, or net ionic equations, balance is key. For example, in the net ionic equation \[\begin{equation}2\mathrm{OH^-} + 2\mathrm{H^+} \rightarrow 2\mathrm{H_2O}\end{equation}\]
there are 2 oxygen atoms and 4 hydrogen atoms on both sides. This consistency confirms that the mass is conserved, and the reaction is correctly balanced.