Complete and balance the following reaction: Ca(OH)_{2(aq)} + HC_2H_3O_{2(aq)} \to _____. Also,...


Complete and balance the following reaction: {eq}Ca(OH)_{2(aq)} + HC_2H_3O_{2(aq)} \to {/eq} _____. Also, write the complete ionic and net ionic equations, if applicable.

Double Displacement Reaction:

A double displacement reaction takes place when two compounds swap ions in order to form new compounds. This type of reaction can be represented by the general equation below:

{eq}\rm AB + CD \to AD + CB {/eq}

Examples of double displacement reactions are precipitation reactions and acid-base neutralization.

Answer and Explanation: 1

The reaction between calcium hydroxide, {eq}\rm Ca(OH)_2 {/eq}, and acetic acid, {eq}\rm HC_2H_3O_2 {/eq}, is an example of a double displacement reaction. In this reaction, the calcium ions, {eq}\rm Ca^{2+} {/eq}, abstract the acetate ions,{eq}\rm C_2H_3O_2^- {/eq} forming calcium acetate, {eq}\rm Ca(C_2H_3O_2)_2 {/eq}, while hydrogen ions, {eq}\rm H^+ {/eq}, pair up with hydroxide ions, {eq}\rm ^-OH {/eq}, to form water, {eq}\rm H_2O {/eq}:

{eq}\rm Ca(OH)_2(aq) + HC_2H_3O_2(aq) \to Ca(C_2H_3O_2)_2(aq) + H_2O(l) {/eq}

To balance this equation, we look at the number of ions on both sides. There is only 1 acetate ion on the reactant side and 2 on the product side. Thus, we add a coefficient of 2 before acetic acid to balance acetate:

{eq}\rm Ca(OH)_2(aq) + 2HC_2H_3O_2(aq) \to Ca(C_2H_3O_2)_2(aq) + H_2O(l) {/eq}

The addition of 2 before acetic acid increased the number of hydrogen ions to 2 on the reactant side. In water, there is only 1 hydrogen ion. Hence, to balance hydrogen ions, we introduce a coefficient of 2 before water giving us the balanced chemical equation below:

{eq}\rm Ca(OH)_2(aq) + 2HC_2H_3O_2(aq) \to Ca(C_2H_3O_2)_2(aq) + 2H_2O(l) {/eq}

To get the complete ionic equations, we split into ions all the compounds with the label (aq) which is short for aqueous and which suggests that the compounds form ions in water:

{eq}\rm Ca^{2+}(aq) + 2^-OH(aq) + 2H^+(aq) + 2C_2H_3O_2^-(aq) \to Ca^{2+}(aq) + 2C_2H_3O_2^-(aq) + 2H_2O(l) {/eq}

To determine the net ionic equation, we eliminate the ions appearing on both sides of the equation which are calcium ion and acetate ions:

{eq}\rm 2^-OH(aq) + 2H^+(aq) \to 2H_2O(l) {/eq}

We can simplify the net ionic equation by removing the coefficients 2:

{eq}\rm ^-OH(aq) + H^+(aq) \to H_2O(l) {/eq}

Learn more about this topic:

Writing Chemical Equations on the AP Chemistry Exam


Chapter 14 / Lesson 6

The AP Chemistry exam includes chemical equation questions about chemical reactions. Learn the tricks involved to master the questions on different types of reactions, and practice them for the AP Chemistry exam.

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