Basic Water and chemistry

Question 1

covalent bonds

Answer 1

sharing of electrons

Question 2

What are non-covalent bonds?

Answer 2

much weaker than covalent bonds, reversible, repeated

Question 3

What are three types of covalent bonds?

Answer 3

1. Ionic Bonds (strongest)
2. H-Bonds
3. Van der Waals Interactions
4. Hydrophobic interactions (weakest)

Question 4

What are ionic bonds?

Answer 4

electrostatic interactions (“salt bridges”) - can be broken down by water

Question 5

What are H-Bonds?

Answer 5

Bonds b/t electronegative atoms (commonly Oxygen and Nitrogen) and Hydrogens; can be disrupted by water

Question 6

What are Van Der Waals Interactions?

Answer 6

electrostatic interactions of partial charges (random, transient asymmetry)

Question 7

What are hydrophobic interactions?

Answer 7

hydrophobic regions of a biomolecule interacting with another hydrophobic molecule

Question 8

What are functional groups?

Answer 8

part(s) of a molecule that can affect the properties and function of that molecule

Question 9

What are the 8 functional groups?

Answer 9

1. Hydrophobic (non-polar) -Hydrocarbon chain/aromatic
2. Hydroxyl (OH)
3. Aldehyde (carbonyl with H and R group attached)
4. Keto (carbonyl with two R groups)
5. carboxyl (carbonyl with OH and R group)
6. Amino (Amine)
7. Phosphate (R group with PO4)
8. Sulfhydryl (R group with SH, can form compunds with other thiols(sulfhydryl bridges))

Question 10

Name 5 distinct characteristics of H2O

Answer 10

1. Polar
2. Involved in H-Bonding
3. Good Solvent for any charged/polar molecules
4. can’t dissolve uncharged/polar molecules
5. Dissociation of water: H2O H1+ + OH1-

Question 11

When the charge distribution in a molecule is not uniform

Answer 11

Polar Molecule (i.e. O is electronegative and H is electropositive)

Question 12

PH

Answer 12

1. Measure of a free hydrogen ion (“proton”) concentration
2. A log scale of proton concentration (H+)
3. Importance: Affects the electrostatic interactions (bonding), which alters the structure and function of a biomolecule.
4. Water/other molecules can dissociate to release H+ protons

Question 13

Measures the extent to which reactants are converted to products by the rxn at equilibrium

Answer 13

Keq

Question 14

Rxn for Keq

Answer 14

[H+][OH-]/[H20]
Where M of [H+] and [OH-] is 10^-7 (each)
and M of [H2O] is 55.5

Question 15

What is a common misconception of equilibrium?

Answer 15

That the substances are present in equal amounts.

Question 16

What is true when a rxn has reached equilibrium?

Answer 16

concentration of reactants and products are unchanging with time (forward and backward rxn have the same time).

Question 17

You can relate pH to hydrogen ion concentration

using the following equation:

Answer 17

pH = - log10 [H+]
(Since, [H+] is 10-7 M… pH = -log10 (10-7) = 7
… which is the pH of pure H2O. )

Question 18

Proton Donor

Answer 18

Acid

Question 19

What is the result when an acid loses a Hydrogen ion?

Answer 19

It becomes (“unprotonated”), resulting in an ionized, conjugate base

Question 20

Proton Acceptor

Answer 20

Base

Question 21

What is the result when an base gains a Hydrogen ion?

Answer 21

It becomes (“protonated”), resulting in an ionized, conjugate acid

Question 22

Equilibrium constant, Ka

Answer 22

Ka = [H+][A-] / [HA]

Question 23

The Henderson-Hasselbach equation allows us to correlate ___ with ___.

Answer 23

pH, pKa

Question 24

What is the Henderson-Hasselbach equation?

Answer 24

pH = pKa + log ([A-] / [HA])

Question 25

What two things can you do using the Henderson-Hasselbach equation?

Answer 25

1. Calculate relative amounts of protonation of acids and bases in a given pH.
2. Calculate change in pH when acid/base is added.

Question 26

What does it mean when pH=pKa?

Answer 26

acid and base are in equal concentrations

when acid is half-associated/dissociated/protonated/unprotonated

Question 27

What is a buffer?

Answer 27

acid-base conjugate pairs that resist changes in pH

Question 28

When are buffers most effective?

Answer 28

at he vicinity of its pKa