Lecture 4: Acid-Base Chemistry Flashcards
organic acids are ___ acids
weak
Buffers are solutions that
resist changes in pH
human blood pH
7.35-7.45
human pH above 7.4
alkalosis
human pH below 7.35
acidosis
what is associated with alkalosis
muscle spasms, convulsions
what is associated with acidosis?
CNS depression, coma, death
3 buffering systems in the body
- bicarbonate
- phosphate
- protein
buffers are often used in lab and are made my mixing appropriate concentrations of
weak acid and its conjugate base
why can buffer resist pH change?
equilibrium between weak acid and conjugate base
if more H atoms are added to a buffer, the equilibrium shifts towards formation of
acid
if more OH ions are added to a buffer, the equilibrium shifts towards formation of
base
le chatelier’s principle
when a stress is applied to a chemical system at equilibrium, it will shift to relieve the stresss
why use a buffer in lab?
dont want reaction liquid to change pH as it may ruin or confound the experiment
titration curve
plot of how the pH changes with amount of OH or H added
the titration curve reveals the best buffering situation, which is where
a solution best resists change when acid/base is added
the best buffering situation occurs when pH is equal to
pKa of acid
when choosing a buffer in the lab, you should choose one that has a similar __ to that of your desired solution
pH
the bicarbonate buffer is used to regulate ___. It involves ___ (ion) and ___ (molecule)
blood pH. Bicarbonate and CO2
the amount of CO2 in blood is strictly controlled by the amount __-
lost while breathing
the phosphate buffer is used to regulate
pH inside cells
the protein buffer is used to regulate
amino acid buffering
all amino acids have at least ___ ionizable groups
2
all amino acids possess 5 components
- alpha carbon
- amino
- carboxyl
- hydrogen
- r chain
the amino and carboxyl group of an amino acid can be ionized based on surrounding
pH
at typical cyto plasm pH, the amino will be ___ and the carboxyl will be ___
protonated; deprotonated
amino acids are typically found in the ___ form
zwitter ion
what is a zwitterion?
a molecule having separate positive and negative charged groups
water ionizes to a very ___ degree
small
pH (log scale) is used because
H concentrations can vary over a vast range
pKa (log scale) is a measure of
the ability of weak acid to dissociate into H ions and CB
pH influences ionization of many biomolecules and thus influences ___ of cell
chemical characteristics and chemistry
