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Chapters 16, 17, and 19
Acids, bases, buffers, thermodynamics
60
Chemistry
Undergraduate 2
10/21/2009

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Term
strong acids
Definition
HCl, H2SO4, HI, HBr, H3O, HClO3, HClO4, HNO3
Term
strong bases
Definition
NaOH, KOH, Ca(OH)2, O2, ionic hydroxides of alkali metals, heavy alkaline earth metals
Term
Bronsted-Lowry Acid
Definition
proton donator
Term
Bronsted-Lowry Base
Definition
proton acceptor
Term
amphiprotic
Definition
can function as a Bronsted-Lowry acid or base depending on what it reacts with
Term
conjugate base
Definition
species that remains when a proton is removed from the acid
Term
conjugate acid
Definition
species that is formed by adding a proton to the base
Term
autoionization
Definition
water ionizes slightly to from H+ and OH-
Term
ion-product constant
Definition
Kw = [H+] [OH-] = 1.0e-14 at 25 degrees C
Term
pH
Definition
-log[H+] or {14 - (-log[OH-])}
Term
acid dissociation constant
Definition
Ka, representative of weak acids, equilibrium constant for (HA) --> (H+) + (A-)
Term
percent ionization
Definition
(concentration ionized / original concentration) x 100
( [H+] equilibrium) / ( [HA] initial) x 100
Term
polyprotic acids
Definition
more than one ionizable proton (Ka1, Ka2...)
Term
base dissociation constant
Definition
Kb, representative of weak bases (amines, NH3...), equilibrium constant for the reaction
B + H2O --> HB+ + OH-
Term
Kw = Ka x Kb
Definition
Term
hydrolysis
Definition
the reaction of ions with water resulting in a pH change
Term
do not undergo hydrolysis
Definition
the cations of the alkali metals and alkaline earth metals, anions of strong acids (always spectator ions in acid-base chemistry)
Term
tendency of a substance to show acid or base characteristics is dependent upon:
Definition
bond polarity, bond strength, X- ion stability
Term
Lewis Acid
Definition
electron pair acceptor
Term
Lewis base
Definition
electron pair donator
Term
pH + pOH = 14
Definition
Term
Ka
Definition
[H+][A-] / [HA]
Term
Kb
Definition
[HB+][OH-] / [B]
Term
common-ion effect
Definition
the dissociation of a weak acid or weak base is repressed by the presence of a strong electrolyte that provides an ion common to the equilibrium
Term
pH = pKa + log (base / acid)
Definition
Term
Ksp
Definition
equilibrium constant that expresses the extent to which the compound disolves, equal to the product of the concentration of the ions involved in the equilibrium each raised to the power of its coefficient
Term
molar solubility
Definition
number of moles of the solute that dissolve in forming a liter of a saturated solution of the solute (mol/L)
Term
solubility
Definition
grams of solute dissolved in L of solution
Term
reversible process
Definition
results in no change in entropy (S=0)
Term
irreversible process
Definition
results in an increase in overall entropy (S>0)
Term
the number of microstates available increases with an increase in:
Definition
volume, temperature, number of molescules
Term
increase in entropy
Definition
increase in temperature, volume or number of particles
Term
if G is negative:
Definition
the reaction is spontaneous
Term
if G is 0:
Definition
equilibrium
Term
if G is positive
Definition
nonspontaneous and work must be applied
Term
isothermal process
Definition
any process that occurs at a constant temperature
Term
at a constant temperature, the entropy of a system is:
Definition
given by the heat absorbed by the system along a reversible path (Qrev) divided by the temperature
Term
W
Definition
number of microstates present
Term
standard molar entropy for an isothermal process is
Definition
equal to -∆H / T
Term
when ∆G is negative
Definition
the process is spontaneous
Term
when ∆G is positive
Definition
the process is nonspontaneous
Term
at equilibrium ∆G is
Definition
equal to 0 and the process is reversible
Term
entropy term
Definition
-T∆S
Term
melting of ice
Definition
∆H>0, ∆S>0, nonspontaneous at low temperatures, and spontaneous at high temperatures
Term
at equilibrium Q=K
Definition
the standard free energy change is directly related to the equilibrium constant for the reaction
Term
calculating [H+] given [OH-]
Definition
[H+] = (1.0e-14 / [OH-])
Term
calculating the pH of a strong acid
Definition
[H+] = [ion], so pH = -log [ion]
Term
calculating the pH of a strong base
Definition
[OH-] = [strong base] so pOH = 14 - (-log [strong base])
Term
calculating Ka from measured pH
Definition
10^(measured pH) = [H+], ICE tablewith [H+] as change, Ka = ([products] / [reactants])
Term
using Ka to calculate pH
Definition
ionization equation, ICE table where change is "x", Ka equation using "x", solve for -log(x)
Term
using Ka to calculate percent ionization
Definition
ICE table using x as change, Ka equation solve for x, if greater than 5% of molar value use the quadratic equation to find [ion], then use [ion] / [original] x100
Term
using pH to determine salt concentration
Definition
pOH = 14 - pH, [OH-] = 10^pOH, ICE table with x as [initial] and change is [OH-], Kb equation solving for x
Term
calculating Ka given Kb
Definition
Ka = (1e-14) / Kb
Term
if common ion is involved in calculating [ion]
Definition
x is small relative to other concentrations
Term
calculating pH of a buffer
Definition
pH = pKa + log ([base] / [acid])
Term
preparing a buffer
Definition
pOH = 14 - pH, [OH-] = 10^pOH, Kb equation solving for [other ion], then [other ion] x volume of solution
Term
calculating pH for strong acid-strong base titration
Definition
find moles of H+ and OH-, ICE table subtracting mol OH- from mol H+, final mol H+ / sum of volumes = [H+]
Term
calculate pH for weak acid-strong base titration
Definition
find moles of acid and base, subtract mol base from mol acid and add mol base to conjugate base, final mol acid / sum of volumes, final mol conjugate base / sum of volumes, Ka equation solving for other concentration
Term
calculating pH at equivalence point
Definition
find mol acid then divide by (volume x2), ICE table with x for change, Kb equation solving for x to find [OH-], then change that to pH
Term
calculating Ksp from Solubility
Definition
write balance ionic equation, use coefficient multiplication to solve for moles not given, Ksp = [products] / [reactants] no solids, or pure liquids
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