Water, Weak Acids and Bases

Question 1

Strong Bonds/Primary Bonds

Answer 1

Strong bonds are between ELEMENTS
Ionic
Covalent
Metallic

Question 2

Ionic Bonds

Answer 2

TRANSFER of electrons
Strongest of the 3 primary bond types
Metal - Nonmetal

Question 3

Covalent Bonds

Answer 3

SHARING of electrons
Second strongest primary bond
Nonmetal - Nonmetal

Question 4

Metallic

Answer 4

SHARING of CONSTANTLY MOVING electrons
Weakest primary bond
Metal - Metal

Question 5

Weak Bonds/Secondary Bonds (Strong–>Weak)

Answer 5

• Weak bonds are between MOLECULES*
  1. Ion-Dipole
  2. H Bonds
  3. Dipole-Dipole
  4. Ion-Induced Dipole
  5. Dipole-Induced Dipole
  6. Dispersion Forces

Question 6

Hydrogen Bonds

Answer 6

When a Hydrogen is COVALENTLY BONDED to a F,N, or O it has the ABILITY to H-bond. Can only H-bond to F, N, or O (electronegative elements)

Question 7

Weak Interactions among Biomolecules in Aq Solvent

Answer 7

Hydrogen Bonds- between neutral groups and peptide bonds
Ionic Interactions- Attraction and Repulsion
Hydrophobic Interactions
Van Der Waals- caused by delocalization of e- around 2 molecules

Question 8

Water as a Liquid and Solid

Answer 8

Liquid: ONE molecule of water binds to ONLY 3.4 molecules of water.
-why? its liquid so its moving

Solid: ONE molecule of water binds to 4 molecules of water.
-why? Solid lattice structure
Ice is less dense than water because it expands

Question 9

Hydrogen Bond Directionality

Answer 9

H-Bonds are stronger when they are straight (puts the positive charge of H directly between two negative charges)
H-Bonds are weaker when there is a bend in the alignment of X—H——X

Question 10

Amphipathic Molecule

Answer 10

Has both Polar and Nonpolar regions

Question 11

Water as a Solvent for Polar Molecules

Think Salt in Water

Answer 11

Ionic bonds (and other polar bonds) dissolve in water spontaneously because the entropy (S) is large due to the disordering of a highly structured lattice breaking down.
^G= ^H - T^S
^G is NEGATIVE

Question 12

Water as a Solvent for Amphipathic/ Amphiphilic Compounds (Think Oil)

Answer 12

Non-Spontaneous Interaction because the non polar region of the molecule causes water to form highly organized “cages” around the polar tail. Organization=negative entropy (S)
^G= ^H - T^S
^G is POSITIVE

Question 13

Water as a Solvent Overview

Answer 13

No matter what molecule you put in water, the molecule will be interrupting water-water hydrogen bonding (and the enthalpy is always +)

• Polar solvents compensate via INCREASE in entropy = negative deltaG = spontaneous
• Non-polar solvents cause a DECREASE in entropy because the water is being forced to organize around the non polar region = positive deltaG = non spontaneous

Question 14

Lipids in Water

Answer 14

Clusters of lipid molecules are more energetically favorable than dispersed lipids because the organization of water is decreased when it doesn’t have to surround each individual lipid.
Micelles are even more favorable because only the polar regions interact with the water causing even less water organization.
Strong interactions NOT due to polar interactions with water, but because its the MOST THERMODYNAMICALLY STABLE

Question 15

Lipid Bilayer

Answer 15

Two rows of lipid molecules with polar heads facing out and hydrophobic/nonpolar tails facing inward. Water inside and outside the bilayer interacting with the polar heads.

Question 16

Micelles

Answer 16

Single row of lipid molecules in a sphere. Polar heads out lipid tails inside the ball. Used to deliver things into the body (drugs)

Question 17

Liposome

Answer 17

Two rows of lipid molecules in a spherical shape where there is water both inside and outside the lipids. Similar to a bilayer but it forms a vesicle rather than a membrane.

Question 18

Enzyme-Substrate Complexes in Water

Answer 18

Thermodynamically favorable because the binding of the Substrate to the Enzyme disrupts the order of the water molecules on the surfaces on the substrate and the enzyme. Entropy increases upon binding.

Question 19

Solutes in Solution

Answer 19

Adding a Solute changes the colligative properties:

1. Boiling Point
2. Vapor Pressure
3. Melting Point
4. Osmotic Pressure

Question 20

Isotonic Solution

Answer 20

No net water movement because solute levels are the same inside and outside the cell

Question 21

Hypertonic Solution

Answer 21

More solute outside of the cell than inside
Causes the water to leave the cell in an attempt to equalize solute levels.
Water leaving the cell causes it to shrink/shrivel

Question 22

Hypotonic Solution

Answer 22

Solute levels are higher inside the cell than outside.

Causes water to flow into the cell = swelling

Question 23

pH and pOH formulas

Answer 23

pH= log (1/[H+]) or
pH= -log(H+)  --------> pH= log ( 1/ [ 1x 10^-7]) = 7

pOH is the same but with [OH-]

Question 24

pH degree of change

Answer 24

pH scale is logarithmic. Therefore two solutions that differ by 1 pH have a difference of 10 times the amount of [H+]
Small changes of pH in the body can be fatal (blood pH of 7.2 is normal, 7.4 can be fatal)

Question 25

Strong vs. Weak Acids and Bases

Answer 25

Strong Acids/Bases COMPLETELY dissociate in water

Weak Acids/Bases PARTIALLY dissociate in water

Question 26

Titration

Answer 26

Add H+ to bases
Add OH- to acids
When pH=pKa there is an equal amount of acid and basin solution. Called the buffer region.

Question 27

Strong Acid: pKa and Ka values

Answer 27

Large Ka
Small pKa
Most of the Acid has been converted into H+ and A-

Question 28

Weak Acid: pKa and Ka

Answer 28

Small Ka
Large pKa
Less acid has dissociated = weaker acid

Question 29

Henderson-Hasselbalch Equation

Answer 29

pH = pKa + log A-/HA
So when [A-] = [HA] you have log 1/1 = 0
so pH=pKa when you have equal concentrations of acid and base
(literally just explains titration curve)

Question 30

Buffers

Answer 30

Minimize pH changes

Question 31

Bicarbonate Buffer System

Answer 31

Carbonic acid and bicarbonate –> CO2

Most important buffer in the body because it keeps our blood pH constant

Question 32

Acidosis

Answer 32

Too much acid in the arterial blood

pH lower than 7.35

Question 33

Alkalosis

Answer 33

Too much base in the arterial blood

pH higher than 7.45

Question 34

Respiratory Acidosis

Answer 34

Impairment of the disposal of CO2 by the lungs so pH levels are too low

Question 35

Respiratory Alkalosis

Answer 35

Results from hyperventilation, excessive exercise etc

Breathe too fast and get rid of too much CO2, pH increases

Question 36

Metabolic Acidosis

Answer 36

Over production of organic acids or inability of kidneys to excrete excess acid. pH is too low

Question 37

Metabolic Alkalosis

Answer 37

Abnormal loss of acid from the body.