A 500 . -mL solution consists of 0.050 mol of solid NaOH and 0.13 mol of hypochlorous acid (HClO

step 1 Question number 129 is a pH calculation after mixing a strong base with a weak acid. So long as

A 500 . -mL solution consists of 0.050 mol of solid NaOH and...

$\mathrm{A} 500 .$ -mL solution consists of 0.050 $\mathrm{mol}$ of solid $\mathrm{NaOH}$ and 0.13 $\mathrm{mol}$ of hypochlorous acid $\left(\mathrm{HClO} ; K_{\mathrm{a}}=3.0 \times 10^{-8}\right)$ dissolved in water. (a) Aside from water, what is the concentration of each species that is present? (b) What is the pH of the solution? (c) What is the pH after adding 0.0050 mol of HCl to the flask?

$\mathrm{A} 500 .$ -mL solution consists of 0.050 $\mathrm{mol}$ of solid $\mathrm{NaOH}$ and 0.13 $\mathrm{mol}$ of hypochlorous acid $\left(\mathrm{HClO} ; K_{\mathrm{a}}=3.0 \times 10^{-8}\right)$ dissolved in water.
(a) Aside from water, what is the concentration of each species that is present?
(b) What is the pH of the solution?
(c) What is the pH after adding 0.0050 mol of HCl to the flask?

Key Concepts

Equilibrium in Weak Acid/Base Reactions

Weak acids and bases do not completely dissociate in solution, leading to an equilibrium between the undissociated form and its ions. Understanding the role of the equilibrium constant (Ka for acids) is essential in predicting the extent of dissociation and adjusting pH calculations when these species are present alongside strong acids or bases.

pH Calculation Methods

Calculating the pH of a solution involves different approaches depending on the system; whether it is a neutralization reaction with excess strong base or acid, or a buffer system containing a weak acid and its conjugate base. For excess strong acid or base, the concentration of H+ or OH– is directly used, while for buffers, the pH is typically estimated using the Henderson?Hasselbalch equation.

Acid?Base Neutralization Stoichiometry

This concept involves calculating the amounts of reactants and products when an acid and a base react. In acid-base reactions, typically one reactant is the limiting reagent, determining the extent of the reaction. A stoichiometric analysis helps to identify which species remain, are completely consumed, or are produced in excess, which is crucial for determining the resultant concentrations in the solution.

Buffer Solutions and the Henderson?Hasselbalch Equation

When a weak acid and its conjugate base are present together in significant amounts, a buffer is formed, which resists changes in pH upon addition of a small amount of strong acid or base. The Henderson?Hasselbalch equation provides a convenient way to relate the pH of the solution to the acid dissociation constant (pKa) and the ratio of the concentrations of the conjugate base to the weak acid.

Transcript

Please give Ace some feedback