Chapter 2: Buffers Flashcards
PH scale equation
pH + pOH = 14
Ka represents
the level of dissociation of the acid
When strong acids are placed in water they
completely dissociate (Ka > 1)
When weak acids are placed in water they
partially dissociate (Ka<1)
Formula for pKa
pKa= -log(Ka)
When to use the Henderson- Hasselbalch equation
When HA and A- are both present in the solution
Midpoint of a titration curve is where
[HA]= [A-]
Buffer definition
Solution whose pH changes very little when small amounts of acid or base are added to it
Phosphate and bicarbonate buffer systems are essential in :
maintaining a cellular pH constant
How do buffers work?
they soak up excess H+ or OH ions when added to a solution
Buffering capacity increases with
increasing concentration of buffering agent
The pH range of a buffer is
+/- 1 from the pKa
Polyprotic acids are
molecules that have multiple groups that can be deprotonated
The titration curve of a polyprotic acid has how many curves?
The same number of groups that can be deprotonated, each connected together and increasing in PH each time
The pKa of 2 closesly associated acid-base groups are:
not independent
What affects the change in pKa of polyprotic acids as they are deprotonated?
The close the groups are, the larger the change in pKa
Primary buffering system in blood
bicarbonate buffering system
If an acidic compound is dissolved in an organic solvent, would it increase the acid’s pKa value?
organic molecules do not have basic properties and cannot pick up any released protons therefore the pKa values would be much higher since protons are not released readily.
