Question

Write balanced complete ionic and net ionic equations for each acid-base reaction. a. \(\mathrm{HI}(a q)+\mathrm{RbOH}(a q) \longrightarrow\) b. \(\mathrm{HCHO}_{2}(a q)+\mathrm{NaOH}(a q) \longrightarrow\) \(\mathbf{c .} \mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q)+\mathrm{LiOH}(a q) \longrightarrow\)

Short answer

Net ionic equations: a) \(\mathrm{H^+}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{H_2O}(l)\), b) \(\mathrm{HCHO}_{2}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{CHO_2^-}(aq) + \mathrm{H_2O}(l)\), c) \(\mathrm{HC}_{2}\mathrm{H}_{3}\mathrm{O}_{2}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{C}_{2}\mathrm{H}_{3}\mathrm{O}_{2}^-(aq) + \mathrm{H_2O}(l)\).

Step-by-step solution

Write the Balanced Molecular Equation for Reaction a

The balanced molecular equation for the reaction between hydroiodic acid (HI) and rubidium hydroxide (RbOH) is: \[\mathrm{HI}(aq) + \mathrm{RbOH}(aq) \longrightarrow \mathrm{RbI}(aq) + \mathrm{H_2O}(l)\]

Write the Complete Ionic Equation for Reaction a

Dissociate all strong electrolytes into ions: \[\mathrm{H^+}(aq) + \mathrm{I^-}(aq) + \mathrm{Rb^+}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{Rb^+}(aq) + \mathrm{I^-}(aq) + \mathrm{H_2O}(l)\]

Write the Net Ionic Equation for Reaction a

Cancel out the spectator ions to find the net ionic equation: \[\mathrm{H^+}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{H_2O}(l)\]

Write the Balanced Molecular Equation for Reaction b

The balanced molecular equation for the reaction between formic acid (\(\mathrm{HCHO}_{2}\)) and sodium hydroxide (NaOH) is: \[\mathrm{HCHO}_{2}(aq) + \mathrm{NaOH}(aq) \longrightarrow \mathrm{NaCHO}_{2}(aq) + \mathrm{H_2O}(l)\]

Write the Complete Ionic Equation for Reaction b

Only NaOH dissociates into ions as formic acid is a weak acid: \[\mathrm{HCHO}_{2}(aq) + \mathrm{Na^+}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{Na^+}(aq) + \mathrm{CHO_2^-}(aq) + \mathrm{H_2O}(l)\]

Write the Net Ionic Equation for Reaction b

Since formic acid is a weak acid, the net ionic equation includes the undissociated form: \[\mathrm{HCHO}_{2}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{CHO_2^-}(aq) + \mathrm{H_2O}(l)\]

Write the Balanced Molecular Equation for Reaction c

The balanced molecular equation for the reaction between acetic acid (\(\mathrm{HC}_{2}\mathrm{H}_{3}\mathrm{O}_{2}\)) and lithium hydroxide (LiOH) is: \[\mathrm{HC}_{2}\mathrm{H}_{3}\mathrm{O}_{2}(aq) + \mathrm{LiOH}(aq) \longrightarrow \mathrm{LiC}_{2}\mathrm{H}_{3}\mathrm{O}_{2}(aq) + \mathrm{H_2O}(l)\]

Write the Complete Ionic Equation for Reaction c

Only LiOH dissociates into ions as acetic acid is a weak acid: \[\mathrm{HC}_{2}\mathrm{H}_{3}\mathrm{O}_{2}(aq) + \mathrm{Li^+}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{Li^+}(aq) + \mathrm{C}_{2}\mathrm{H}_{3}\mathrm{O}_{2}^-(aq) + \mathrm{H_2O}(l)\]

Write the Net Ionic Equation for Reaction c

Since acetic acid is a weak acid, the net ionic equation includes the undissociated form: \[\mathrm{HC}_{2}\mathrm{H}_{3}\mathrm{O}_{2}(aq) + \mathrm{OH^-}(aq) \longrightarrow \mathrm{C}_{2}\mathrm{H}_{3}\mathrm{O}_{2}^-(aq) + \mathrm{H_2O}(l)\]

Key concepts

Ionic Equations

Ionic equations represent the breakdown of compounds into individual ions when they are dissolved in water, commonly seen in the context of precipitation, neutralization, and redox reactions. These equations can significantly enhance the understanding of reaction dynamics because they depict the actual forms of the substances involved in the reaction.

An ionic equation is similar to a molecular equation but provides a more detailed depiction. It allows us to separate the strong electrolytes into their respective ions which is what happens in solution. For example, in step 2 for reaction a, hydroiodic acid (HI) and rubidium hydroxide (RbOH) are represented as \(\mathrm{H^+}(aq) + \mathrm{I^-}(aq) + \mathrm{Rb^+}(aq) + \mathrm{OH^-}(aq)\). It's important to identify strong electrolytes as they completely dissociate in water and participate in the reaction as ions. Understanding ionic equations helps in grasping the nuances of electrolyte behavior in aqueous solutions.

Net Ionic Equations

Net ionic equations distill the reaction down to its essence by displaying only the chemical species that are actually involved in the reaction. They are derived from the complete ionic equation by removing the spectator ions, which are the ions that do not participate in the reaction. These equations provide insight into which ions are responsible for the chemical change.

An example is seen in step 3 for reaction a, where the spectator ions \(\mathrm{Rb^+}(aq)\) and \(\mathrm{I^-}(aq)\) have been omitted to highlight the actual process of water formation through the reaction of \(\mathrm{H^+}(aq)\) and \(\mathrm{OH^-}(aq)\). Learning to write net ionic equations is a fundamental skill in chemistry as it aids students in identifying the active participants in reactions and predicting the products.

Acid-Base Reactions

Acid-base reactions are specific types of chemical procedures where an acid reacts with a base to form a salt and water. This process is also known as neutralization. The strength of an acid or base is a key factor in determining how they behave in a reaction and is essential for writing the corresponding equations.

For instance, in the solutions for reactions b and c, we encounter formic acid and acetic acid. Both of these are weak acids and do not dissociate completely in solution, which is contrasted with strong bases like NaOH and LiOH that do dissociate completely. So, the complete ionic equations for reactions involving weak acids show the intact acid molecule, as seen in step 5 and step 8. Understanding the difference between strong and weak acids or bases is critical for predicting the course of these reactions and their resultant ionic, and net ionic equations.