Properties of Acids and Bases Flashcards
Acids
Donate a proton (H+ or H3O+)
Monoprotic Acid
Can only donate one proton
HCL –> H+ +Cl-
Diprotic Acid
Can donate two protons
H2SO4 –> H+ +HSO4-
HSO4- –> H+ +SO4 (2-)
Triprotic Acid
Can donate three protons
H3PO4 –> H+ +H2PO4-
H2PO4- –> H+ +HPO4 (2-)
HPO4 (2-) –> H+ +PO4 (3-)
Bases
Reacts with acids to produce salt and water
Hydroxide
NaOH –> Na+ +OH-
Oxide (with water)
Na2O + H2O –> 2Na+ + 2OH-
Ammonia (with water)
NH3 + H2O –> NH4+ +OH-
Acid/base strength
Strong acid/base dissociates completely in water
Weak acid/base dissociates partially in water
Acid/base concentration
Concentrated: large amount of acid/base dissolved in solvent
Dilute: small amount of acid/base dissolved in solvent
Bronsted Lowry Acid
Donates a proton (H+)
Bronsted Lowry Base
Accepts a proton (H+)
Conjugate Acid Base Pairs
Two species that differ by a proton
An acid donates a proton to become a conjugate base
A base accepts a proton to become a conjugate acid
Amphiprotic Substance
Can act as an acid or base
pH+ pOH
14
Calculating pH with H+ concentration (same for oH)
pH = -log H+ concentration
Calculating H+ concentration with pH (same for OH- concentration)
H+ concentration = 10 ^ -pH
Ionic Product Constant of Water
Equilibrium constant for the reaction in which water acts as both a base and an acid simultaneously
H2O (reversible arrow) H+ + OH-
Kw = 10^-14
Kw= Ka X Kb
pKa (same for pKb)
-log Ka
Initial pH on a titration curve
Shows if acid or base is in conical flask, and strength of acid/base
Can calculate initial H+ concentration using pH
Equivalence point on a titration curve
pH value where all moles of base have reacted with all moles of acid in conical flask (solution is neutral)
Half equivalence point on titration curve
When half the volume of base that is required to react with all the moles of acid has been added
pH = pKa at this point
Buffer region on titration curve
Only occurs with weak acid/base in conical flask
Region before equivalence point where pH changes slowly due to weak acid/base behaving as a buffer - lots of undissociated molecules shifting right to replace H+
Strong Acid Strong Base Titration Curve
Initial pH is low
Equivalence point when pH = 7
No buffer region
Weak Acid Strong Base Titration Curve
Initial pH is higher than strong acid
Equivalence point when pH > 7
Buffer region
Strong Acid Weak Base Titration Curve
Initial pH is lower than strong base
Equivalence point when pH < 7
Buffer region
Acid dissociation constant
When acid dissolves in water it produces an anion and a hydronium ion ( H3O+ )
HA + H2O <–> H3O+ + A-
Acid dissociation constant expression
HA + H2O <–> H3O+ + A-
Ka = [H3O+][A-]/[HA]
Ka value only applies to weak acids as strong acids completely dissociate
Large Ka value means a stronger acid, as there are more products meaning more dissociation
Base dissociation constant
When a base dissolves in water it produces a cation and a hydroxide ion
B + H2O <–> BH+ + OH-
Kb values only applies to weak bases as strong bases completely dissociate
Large Kb value means a stronger base, as there are more products meaning more dissociation
Base dissociation constant expression
B + H2O <–> BH+ + OH-
Kb = [BH+][OH-]/[B]
Kw
Ka x Kb
pKa
pKa is to Ka what pH is to [H+]
pKa = -log Ka
pKa values only apply to weak acids as strong acids completely dissociate
Weak acid has a __ conjugate base
strong
Strong acid has a __ conjugate base
weak
