Acid-Base Fundamentals and Titrations

This set of flashcards covers fundamental concepts related to acid-base chemistry, titrations, buffers, and complex ions, as discussed in the lecture.

Indicator

A weak acid or base that changes color between its acid and base form.

Base ionization constant ($K_b$)

The equilibrium constant for the reaction of a base with water.

Acid dissociation constant ($K_a$)

The equilibrium constant for the reaction of a substance with water to form its conjugate base and hydronium ion.

Amphiprotic molecule

A molecule (like water) that can behave as either an acid or a base.

Autoionization

The process where two water molecules react to form a hydronium ion and a hydroxide ion.

Leveling effect

A phenomenon where the strength of any strong acid is reduced to the strength of the hydronium ion (the strongest acid possible in water).

Midpoint (half-equivalence point)

The point in a weak acid/strong base titration where the pH is equal to the $pK_a$.

Acidic solution (pH less than 7)

The pH at which the indicator should change for a weak base/strong acid titration.

Diprotic acid

An acid that has a titration curve with two steps; typically if the $K_a$ values differ by a factor of 1000.

Buffer

A solution that resists pH change when a strong acid or base is added.

Buffer range

The effective pH range for a buffer, typically within 1 $pK_a$ unit of the acid.

Number of oxygen atoms

In oxoacids, the factor that increases acid strength.

Hydrofluoric acid (HF)

Weaker than hydrochloric acid (HCl) because the hydrogen-fluorine bond is stronger than the hydrogen-chlorine bond.

Trichloroacetic acid

Stronger than acetic acid due to chlorine atoms being more electronegative than hydrogen atoms (inductive effect).

Common Ion Effect

The reduction in solubility of an ionic compound due to the presence of one of its constituent ions already in solution.

Complexing agents

Substances added to solutions to react with metal ions (like $Ca^{2+}$ and $Mg^{2+}$) to increase solubility or prevent interference.

Lewis acid

In a complex ion reaction, the role of the metal ion as an electron pair acceptor.

Formation constant ($K_f$)

The equilibrium constant for the reaction of a metal ion with a Lewis base to form a complex.

Ion Product ($Q$)

A value describing concentrations that are not necessarily at equilibrium; if $Q > K_{sp}$, the solution is supersaturated and will precipitate.