Questions: Chem 111B Worksheet 4- Acids and Bases 1. Consider the dissociation of water: 2 H2O(l) ⇌ H3O+ + OH^-, Kw=1.00 × 10^-14 at 25°C a. Express the equilibrium relationship for this reaction:

Chem 111B
Worksheet 4- Acids and Bases
1. Consider the dissociation of water:
2 H2O(l) ⇌ H3O+ + OH^-, Kw=1.00 × 10^-14 at 25°C
a. Express the equilibrium relationship for this reaction:

Transcript text: Chem 111B Worksheet 4- Acids and Bases 1. Consider the dissociation of water: \[ 2 \mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}_{3} \mathrm{O}^{+}+\mathrm{OH}^{-}, K_{w}=1.00 \times 10^{-14} \text { at } 25^{\circ} \mathrm{C} \] a. Express the equilibrium relationship for this reaction:

Solution

Solution Steps

Step 1: Understanding the Reaction

The dissociation of water is a chemical equilibrium process where water molecules dissociate into hydronium ions (\(\mathrm{H}_3\mathrm{O}^+\)) and hydroxide ions (\(\mathrm{OH}^-\)). The equilibrium constant for this reaction is denoted as \(K_w\).

Step 2: Writing the Equilibrium Expression

For the given reaction: \[ 2 \mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}_{3} \mathrm{O}^{+} + \mathrm{OH}^{-} \] The equilibrium expression is written in terms of the concentrations of the products over the reactants. However, since water is a pure liquid, its concentration is not included in the equilibrium expression.

Step 3: Formulating the Equilibrium Constant Expression

The equilibrium constant expression for the dissociation of water is: \[ K_w = [\mathrm{H}_3\mathrm{O}^+][\mathrm{OH}^-] \] where \([\mathrm{H}_3\mathrm{O}^+]\) and \([\mathrm{OH}^-]\) are the molar concentrations of the hydronium and hydroxide ions, respectively.