General Chemistry II Review: Chapter #17 (Additional Aqueous Equilibria) and Chapter #18 (Chemical Thermodynamics)

This is review for the third midterm.

What components make a buffer solution?

A buffer solution contains a weak acid (or base) and its conjugate base (or acid), typically as a salt, sharing a common ion.

Why does the solubility of AgCl increase when NaOH is added?

OH⁻ reacts with Ag⁺ to form AgOH, removing Ag⁺ from the equilibrium. This shifts the dissolution equilibrium right, increasing AgCl solubility.

How can you determine pKₐ using buffer solutions?

Use the Henderson-Hasselbalch equation: pH = pKa + log([A⁻]/[HA]). Rearranging gives pKa = pH - log([A⁻]/[HA]).

What effect does a common ion have on solubility?

A common ion decreases the solubility of a salt due to the common ion effect, shifting equilibrium toward the undissolved solid.

Which titrations have buffer regions?

Only titrations involving a weak acid or base (not strong acid-strong base) have buffer regions before the equivalence point.

How do you find pH after adding strong acid to a buffer?

Write a neutralization reaction (strong acid + base component), adjust concentrations, and use the Henderson-Hasselbalch equation.

How do you calculate Kₛₚ from ion concentrations?

Use the dissociation equation to set up an ICE table, find equilibrium concentrations, and plug into Kₛₚ expression.

What happens when HCl is added to an NH₃/NH₄⁺ buffer?

H⁺ reacts with NH₃ to form NH₄⁺, decreasing NH₃ and increasing NH₄⁺ concentrations.

What is the condition for spontaneity in thermodynamics?

A process is spontaneous when ΔG_sys < 0. Alternatively, ΔS_univ = ΔS_sys + ΔS_surr > 0.

How do you calculate volume at equivalence point in titration?

Use stoichiometry from the balanced equation and molarity-volume relationships to find required titrant volume.

How do you calculate the molar solubility of a salt from its Kₛₚ?

Write the dissociation equation and set up an ICE table. Express Kₛₚ in terms of x (molar solubility), then solve algebraically.