C483 EXAMINATION QUESTIONS AND ANSWERS
Solubility - depends on dielectric constant and polarity
like dissolves like
Residue - Monomers in a polymer
Free Energy - Energy Available to do work in a system or reaction
Enthalpy - total heat or energy of a system
entropy - A measure of disorder or randomness.
intramolecular forces - Forces within molecules
H-Bonds
Dipole-Dipole
LDF
van der Waals
Hydrophobic Effect - Exclusion of nonpolar substances from an aqueous solution
Non-polar molecules do not interact wiht H2O
Amphipathic compounds - Compounds with both hydrophobic and hydrophilic portions
(ex. phospholipids in cell membranes)
Auto-Ionizations - H2O "self-ionizes" in solution and "proton jumping" occurs where
water molecules can create a network in solution so that the "acid" is spread out across the
solution and all the water molecules are moving and transferring protons around to create
hydronium
pH - Concentration of hydrogen ions in a solution (-log [H+])
pKa - -log (concentration of products/ concentration of reactants)
pH of strong acid solutions - strong acids completely dissociate in solution
amount and strength of acid affects pH change
, little strong acid in
solution can sometimes change pH more than more weak acid in solution
Weak Acids - do not completely dissociate in solution
lower Ka and higher pKa
Henderson-Hasselbalch - pH = pKa + log[A-][HA]
A- = proton acceptor
HA = proton donor
Ionization State - at different pHs, what is the charge/ionization state of particular
molecules?
ex) phosphate H3PO4 has 3 pKas - 2.2, 7.2, and 12.7
use this information to know the charge of a phosphate at different pHs
ex) @ pH 2.2, phosphate is 50/50 in all protonated/1 deprotonated form and @ pH 4, it is
mostly in its 1 deprotonated (-1 charge) form
titration curves - show the points at which a substance is deprotonated
ex) titration curve of phosphate shows pKas of the molecule at midpoints
Buffer capacity - depends on pKa and concentration of CA/CB mix
effective buffers also do not let the pH of a solution change much
this means they "soak up" the acid or base in solution that would be attempting to change the
pH
the capacity of a buffer is within 1 unit of its pKa of pH on either side
Solubility - depends on dielectric constant and polarity
like dissolves like
Residue - Monomers in a polymer
Free Energy - Energy Available to do work in a system or reaction
Enthalpy - total heat or energy of a system
entropy - A measure of disorder or randomness.
intramolecular forces - Forces within molecules
H-Bonds
Dipole-Dipole
LDF
van der Waals
Hydrophobic Effect - Exclusion of nonpolar substances from an aqueous solution
Non-polar molecules do not interact wiht H2O
Amphipathic compounds - Compounds with both hydrophobic and hydrophilic portions
(ex. phospholipids in cell membranes)
Auto-Ionizations - H2O "self-ionizes" in solution and "proton jumping" occurs where
water molecules can create a network in solution so that the "acid" is spread out across the
solution and all the water molecules are moving and transferring protons around to create
hydronium
pH - Concentration of hydrogen ions in a solution (-log [H+])
pKa - -log (concentration of products/ concentration of reactants)
pH of strong acid solutions - strong acids completely dissociate in solution
amount and strength of acid affects pH change
, little strong acid in
solution can sometimes change pH more than more weak acid in solution
Weak Acids - do not completely dissociate in solution
lower Ka and higher pKa
Henderson-Hasselbalch - pH = pKa + log[A-][HA]
A- = proton acceptor
HA = proton donor
Ionization State - at different pHs, what is the charge/ionization state of particular
molecules?
ex) phosphate H3PO4 has 3 pKas - 2.2, 7.2, and 12.7
use this information to know the charge of a phosphate at different pHs
ex) @ pH 2.2, phosphate is 50/50 in all protonated/1 deprotonated form and @ pH 4, it is
mostly in its 1 deprotonated (-1 charge) form
titration curves - show the points at which a substance is deprotonated
ex) titration curve of phosphate shows pKas of the molecule at midpoints
Buffer capacity - depends on pKa and concentration of CA/CB mix
effective buffers also do not let the pH of a solution change much
this means they "soak up" the acid or base in solution that would be attempting to change the
pH
the capacity of a buffer is within 1 unit of its pKa of pH on either side
