Chapter 2 - Water Flashcards
What hybridization is the oxygen atom in water? Leads to what?
sp3 hybridized; Leads to a tetrahedral electron domain geometry (109.5 degrees)
The presence of two lone pairs results in a ___ molecular geometry (H–O–H, θ = ____)
bent; 104.5°
What is the most abundant cell in all living cells? What percentage?
Water; 60-90% by mass
Describe the hydrolysis of water.
Slow, most are thermodynamically favorable (–ΔG).
What kind of bonding interaction does hydrogen have in water?
Strong dipole-dipole interaction of hydrogen bonding.
Diffusion rates of small molecules (~__%) in cells are ____ impacted vs. large molecules (~__-__%), relative to pure water.
75; less; 5-10
Does solute tend to be higher or lower within cells relative to their surrounding areas? Causes what?
Higher; water to diffuse into cells
Define osmosis.
The process where a solvent diffuses through a semi-impermeable membrane from a region of lower solute concentration to a region of higher solute concentration.
Why is osmotic pressure required?
It is the pressure required to prevent osmosis.
The hydrophobic effect is responsible for…
self-assembly of amphipathic compounds in aqueous solution, can form micelles, monolayers, or bilayers and improve solubility of nonpolar solutes.
List 2 things about noncovalent interactions.
H-bond, charge-charge interactions are electrostatic interactions b/w 2 charged particles
NONCOVALENT INTERACTIONS: What is a salt bridge?
Ion pairing between oppositely-charged functional groups.
NONCOVALENT INTERACTIONS: Define Van der Waals forces.
Interactions b/w molecules with permanent or transient dipole moments (attractive or repulsive).
NONCOVALENT INTERACTIONS: Describe hydrophobic interactions.
Interactions b/w nonpolar regions or molecules; Individually-weak interactions (~3kJ/mol)
What is the acid-dissociation constant (Ka)?
The equilibrium constant for the ionization of an acid in water.
What is the Henderson–Hasselbalch Equation?
pH = pKa + log ([base]/[acid])
How are buffers prepared?
Prepared from a weak acid and its conjugate base, an aqueous solution which resists changes in pH.
Define buffer capacity.
The amount of acid (or base) that can be added to a buffer solution without large pH changes.
How is the buffer capacity determined?
By the CA and CB - the more concentrated the buffer solution,
the greater the buffer capacity
What is primarily responsible for
the buffer capacity of blood plasma?
The carbonic acid–bicarbonate–carbonate buffer system.
pKa1 of H2CO3 is ___, close to the target buffer of pH ___.
6.4; 7.4
