Questions: 9. Write the balanced chemical equation for the equilibrium that is established when acetic acid is dissolved in water. Include the chemical formulas for all reactants and products, any stoichiometric coefficients and all physical states. Recall that when a substance is dissolved in water, the physical state in a chemical reaction is aqueous (aq). Solve here: CH3COOH(aq) + H2O(l) ⇌ CH3COO^-(aq) + H3O^+(aq) 10. Based on the reaction in Question 9, write the expression for the equilibrium constant (Ka) of acetic acid.

9. Write the balanced chemical equation for the equilibrium that is established when acetic acid is dissolved in water. Include the chemical formulas for all reactants and products, any stoichiometric coefficients and all physical states. Recall that when a substance is dissolved in water, the physical state in a chemical reaction is aqueous (aq).
Solve here: CH3COOH(aq) + H2O(l) ⇌ CH3COO^-(aq) + H3O^+(aq)
10. Based on the reaction in Question 9, write the expression for the equilibrium constant (Ka) of acetic acid.

Transcript text: 9. Write the balanced chemical equation for the equilibrium that is established when acetic acid is dissolved in water. Include the chemical formulas for all reactants and products, any stoichiometric coefficients and all physical states. Recall that when a substance is dissolved in water, the physical state in a chemical reaction is aqueous (aq). Solve here: $\mathrm{CH}_{3} \mathrm{COOH}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{CH}_{3} \mathrm{COO}^{-}(\mathrm{aq})+\mathrm{H}_{3} \mathrm{O}^{\mp}(\mathrm{aq})$ 10. Based on the reaction in Question 9, write the expression for the equilibrium constant $\left(\mathrm{K}_{\mathrm{a}}\right)$ of acetic acid.

Solution

Solution Steps

Step 1: Understanding the Equilibrium Reaction

The equilibrium reaction for acetic acid ($\mathrm{CH}_3\mathrm{COOH}$) dissolving in water is given by:

\[ \mathrm{CH}_3\mathrm{COOH}(\mathrm{aq}) + \mathrm{H}_2\mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{CH}_3\mathrm{COO}^-(\mathrm{aq}) + \mathrm{H}_3\mathrm{O}^+(\mathrm{aq}) \]

This reaction shows acetic acid donating a proton to water, forming acetate ions ($\mathrm{CH}_3\mathrm{COO}^-$) and hydronium ions ($\mathrm{H}_3\mathrm{O}^+$).

Step 2: Writing the Equilibrium Constant Expression

The equilibrium constant expression for the dissociation of acetic acid in water is represented by the acid dissociation constant, $K_a$. For the reaction:

\[ \mathrm{CH}_3\mathrm{COOH}(\mathrm{aq}) + \mathrm{H}_2\mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{CH}_3\mathrm{COO}^-(\mathrm{aq}) + \mathrm{H}_3\mathrm{O}^+(\mathrm{aq}) \]

The expression for $K_a$ is:

\[ K_a = \frac{[\mathrm{CH}_3\mathrm{COO}^-][\mathrm{H}_3\mathrm{O}^+]}{[\mathrm{CH}_3\mathrm{COOH}]} \]

Note that the concentration of water is not included in the expression because it is a pure liquid and its concentration is considered constant.