acids + bases Flashcards
acid
proton doner
base
proton acceptor
acid-base reaction
transfer of a single proton from one species to another
Kᵥᵥ
1) autoprotolysis constant
2) [H₃O⁺][OH⁻]
3) 1 x 10⁻¹⁴
Why is pure water neutral?
equal concentrations of H₃O⁺ + OH⁻
pH =
-log[H₃O⁺]
[H₃O⁺] =
10⁻ᵖᴴ
Kₐ
1) acidity constant
2) [H⁺][A⁻]/[HA]
K₆
1) basicity constant
2) [BH⁺][OH⁻]/[B]
pKₐ =
-log Kₐ
pK₆ =
-log K₆
The larger the Kₐ, the ? the acid
stronger
The smaller the Kₐ, the ? the acid
stronger
Kₐ K₆ =
Kᵥᵥ
pKₐ + pK₆ =
pKᵥᵥ
binary acid
acid containing H and only one other element, generally a non-metal
Does acidity increase or decrease as we proceed down any group?
increase
Why does acidity increase as we proceed down any group?
decreasing bond dissociation enthalpy
oxoacid
acid composed of hydrogen, oxygen, + some other element
What feature is common to all oxoacids?
O-H group bonded to some central atom
buffer solution
contains appreciable amounts of both a weak acid/base + its conjugate base/acid
What is the pH range over which a buffer is effective determined by?
pKₐ / pK₆ + ratio of conjugate pairs present in solution
How can the pH of a buffer solution be calculated?
Henderson-Hasselbalch equation
Henderson-Hasselbalch equation
1) pH = pKₐ + log ([A⁻]/[HA])
2) pH = pKₐ + log (nA⁻/nHA)
When do buffer solutions work most efficiently?
when the ratio of [A⁻] to [HA] is close to 1
When does pH = pKₐ?
when [A⁻] = [HA]
buffer capacity
measure of how much H₃O⁺ + OH⁻ that can be added without causing a significant change in pH
endpoint
pH at which the colour of the acid-base indicator changes
equivalence point
pH at which the reaction stoichiometry is satisfied
