Acid-base Chemistry and Buffering Systems Flashcards
What is a buffer?
A solution composed of a weak acid and its conjugate base that resists change in pH.
The degree to which a particular weak acid/conjugate base pair will constrain pH near a given value will depend on the __________.
dissociation tendency of the acid
The optimal buffering occurs at a pH equal to its natural _____.
pka
The degree to which a buffer solution will continue to resist change with ongoing addition of acid or base is also determined by the ______.
the total concentrations of buffering agents present
The total buffering capacity of a weak acid as a function of pH is determined by its ______ and _______.
pka; concentration of buffering species present
What is the relationship that describes how experimental buffers are established?
Henderson-Hasselback equation
What is the Henderson-Hasselback equation?
pH = pKa + log ( [A-] / [HA] )
An aqueous solution with a pH of 5 has an abundance of free H3O+ that is _____ times that of a solution with a pH of 6.
10
Lower pH means solution is ____.
Stronger acid
Higher pH means solution is
Stronger base
A solution with a high number of hydrogen ions is ____ and has a ___ pH value
acidic; low
A solution with a high number of hydroxide ions is ____ and has a ___ pH value
basic; high
The pH scale ranges from ___ to ___
0; 14
pH of 7 is ____
neutral
What term means that a substance, like water, can act as either an acid or a base?
amphoteric
An acid is a proton ___ and a base is a proton _____.
donor; acceptor
A buffer is made of a ____ acid and its ____ base.
weak; conjugate
Name three examples of weak acid.
HF, HNO2, H2SO3, H3PO4
Name 3 examples of strong acids.
HCl, HNO3, HI, HClO4, HClO3, HBr
_________ dissociate completely into their ions in water, yielding one or more protons per molecule.
Strong acids
The conjugate base is simply the ______ form of the intact acid.
deprotonated
What is the medium of life?
water
Is water a base or acid?
It can be either
What is K_a?
Acid dissociation constant; equilibrium constant
The greater the tendency to dissociate, the _____ the acid, the higher the _____
stronger; pKa
Weak acids exhibit K_a that is ____ 1
Less than
What is the relationship between pka and Ka
pKa = -log(Ka)
The optimal buffering capacity of a weak acid will be obtained when the pH of a system is ___ to the pKa of the acid
=
When setting up a buffer for an experiment, a ____ acid with a pKa near the target should be used.
weak
What were the two types of buffering systems prepared in the Acid-Base Chemistry and Buffering Systems Lab?
- Tris buffer; and
2. Phosphate buffer
______ is a triprotic, capable of donating up to 3 protons.
Phosphoric Acid
