Acids/Bases: Quiz 3 Flashcards
weak acid law
Ka= [H3O+][A-]/[HA]
calculations that require an ICE box
asked to find [H3O+], pH, Ka, or initial concentration
percent ionization equation
equation used to support the assumption that the value of x in the [HA] at equilibrium is neglible
%I=
[H3O+] at equilibrium / [HA] x100
hydrolysis
reaction between an ion and water that produces a conjugate acid or base that effects the concentration of hydronium or the hydroxyl ion; the parent acid and parent base of a salt helps predict the change in [H3O+] or [OH-]
hydrolysis: neutral salts
a salt that contains the anion of a strong acid and the cation of a strong base that produces a neutral solution in water
hydrolysis: basic salts
salts that contain the cation of a strong base and the anion of a weak acid that form a basic solution in water
hydrolysis: acid salts (type 1)
salts that contain the cation of a weak base and the anion of a strong acid that produces an acidic solution in water
hydrolysis: acid salts (type 2)
salts with the anion of a strong acid and the cation is a small highly charged metal ion that produces an acidic solution in water; Al, Fe, Cr, Sn, Cu, Be; 6 water molecules react with them
hydrolysis: mixed salts
salts that contain the anion of a weak acid and the cation of a weak base that can produce either a basic or acidic or neutral solution; write the hydrolysis equation for both ions and then look up or calculate the Ka and Kb values to determine the pH prediction of the solution in water
hydrolysis: salts with amphiprotic ions
salts with the cation of a strong base and the anion is amphiprotic that can produce an acidic, basic, or neutral solution
buffer
solution that resists changes in pH following the addition of relatively small amounts of a strong acid or base; usually made from a weak acid and its conjugate base; the concentrations of the weak acid and conjugate base should roughly be equal and be of appreciable concentrations
2 factors that affect the pH of a buffer
- Ka value
- ratio between the weak acid and its conjugate base concentrations
acid buffers
buffers that are in the acidic range of the pH scale
base buffers
buffers that are in the basic range of the pH scale
[OH-]=
Kb[B]/[HB+]
[H3O+]=
Ka[HA]/[A-]
Henderson-Hasselbalch Equation def
equation used when preparing a buffer to target a specific pH; use this on AP exam when doing buffer calculations
Henderson-Hasselbalch Equation
pH= pKa +log([A-]/[HA])
buffer capacity
amount of an acid or base that a buffer can neutralize before pH drastically changes; high capacity buffers neutralize acids and bases better than low capacity buffers, but high capacity buffers are more reactive
to be effective, the ratio of the weak acid concentration to the conjugate base concentration must be in a range:
10> [A-]/[HA] > 0.10
-ideally the ratio should be 1.0
calculating the volume of a titrant given pH
using the antilogarithm of the pH or pOH as well as stoichiometry, the volume of the titrant can be calculated
calculating percent purity
impure solid acids and bases can be dissolved in pure water and the mass of the pure solid can be calculated through stoichiometry
percent purity equation
mass of pure solute/mass of impure solute x 100
acid-base indicators
solution that changes color in the presence of an acid or base
endpoint/transition point
point in the titration where the indicator changes color
universal indicator
indicator made of lots of acid-base indicators that can turn every color of the rainbow; due to the complexity of indicator molecules, short-hand is used
at the endpoint,
[in-]=[Hin], Ka=[H3O+], pKA=pH
