Acids & Bases

Question 1

4 Properties of Water

Answer 1

Polar
Universal Solvent
High Heat Capacity
High Heat of Vaporization
High Dielectric Constant

Question 2

What shape is water molecule?

Answer 2

Tetrahedal

Question 3

How can water molecules H-bond?

Answer 3

Partial + of H and partial - of O allow it to H-bond and thus be a good solvent (good for hydrophilic molecules)

Question 4

What attraction can O have?

Answer 4

Electrostatic attraction with positively charged atoms

Question 5

Why are H-bonds important?

Answer 5

Hold proteins together (alpha-Helix & beta-sheet)
Nucleic acid structure
Enzyme binding mechanisms
Ligand binding
DNA double helix
Water-sugar bonding

Question 6

Hydrophobic interaction?

Important hydrophobic interactions

Answer 6

Non-polar greasy molecules clump together to exclude water

Proteins, nucleic acids, lipid micelles, polysaccharides, membranes, lipoproteins

Question 7

Amphipathic

Answer 7

Molecules that are hydrophobic on one end and hydrophilic on another end (detergent or fatty acid)

Question 8

Micelle

Answer 8

hydrophilic exterior interacts with h=water around it, hydrophobic core

Question 9

Ionic bond

Answer 9

F = e1e2/Dr^2, attractive or repulsive force btw like or unlike charges

Question 10

van Der waals

Answer 10

weak interactions that act only at a specific region (sinusoidal short curve)

Question 11

Strong interactions vs. weak interactions

Answer 11

Strong: covalent bonding (C-H, C-C) [100 kcal/mole]
Weak: H-bond, ionic bond, van der waals, hydrophobic (<10 kcal/mol)

Question 12

What are some body buffers?

Answer 12

Phosphate, bicarbonate, hemoglobin

Question 13

Acid

Answer 13

Proton donor HA

Question 14

Base

Answer 14

Proton acceptor A-

Question 15

Strong acid dissociation

Answer 15

completely

Question 16

What does the strength of the weak acid depend upon?

Answer 16

pK value

Question 17

What is Kd?

Kw?

Answer 17

Dissociation constant of water, or Kw

Kw = [H+][OH-] = 10^-14

Question 18

What is relationship between Kd and acid strength?

Answer 18

Kd is a measure of how much an acid will dissociate. Therefore if the Kd is high, then the acid will be a strong acid.

Question 19

Define pK mathematically

Answer 19

pK = -log[K]

Question 20

Buffer, it’s composition

Answer 20

Solution that resists change in pH. Contains acid and conjugate base

Question 21

Where on a titration curve is a buffer shown?

Answer 21

Where pH change is small when strong A or strong B is added

Question 22

What is buffer capacity?

Answer 22

Total concentration of acid and base in solution. Higher the concentration of buffer, the more effective it acts as a buffer

Question 23

What is bodily blood pH?

Answer 23

7.4

Question 24

What can pH affect?

Answer 24

Protein conformation, enzyme function, solubility, transport of compounds

Question 25

When does pH = pK

Answer 25

HA = A-

Question 26

What range does the buffering range sit?

Answer 26

+- 1 pH unit of pK of reactive group, whether acid or amine

Question 27

Polyprotic

Answer 27

Use Ka values in between to calculate relative to Henderson-Hasselbach

Question 28

Henderson-Hasselbach

Answer 28

pH = pK +log[A-/HA]

Question 29

Law of electroneutrality

Answer 29

sum of + charges = sum of - charges

Question 30

pKa of bicarbonate

Answer 30

6.1

Question 31

What buffers blood at 7.4?

Answer 31

Largely bicarbonate
Small phosphate
Very small protein

Question 32

What enzyme works in the bicarbonate buffer system?

Answer 32

Carbonic anhydrase

Question 33

Explain bicarbonate buffer system

Answer 33

Carbonic anhydrase converts CO2 and water to carbonic acid. Carbonic acid then dissociates to from bicarbonate and H+