Water, Buffers, And Weak Interactions

Question 1

Why do lipids separates

Non polar lipids have a stronger affinity for _____

polar lipids have a stronger affinity for ____

Answer 1

Due to diff affinity of non polar and polar components

Mobile phase (travel faster)

Stationary phase

Question 2

What causes hydrogen bonding

Answer 2

Electronegativity differences

Question 3

What is a hydrogen bond donor and acceptor

Answer 3

Donor: the this attached to the H thats h bonding

Acceptor: the thing that the h is interacting with

Question 4

How long is a hydrogen bond

How long is the covalent bond between the H and its electronegative atoms

When is hydrogen bond the strongest

Answer 4

3 Angstroms (donor to acceptor distance)

2.0 (h to acceptor distance, h bridge distance)

0.9 angstroms

When the angle at the hydrogen is 180

Question 5

What type of interaction is a hydrogen bond

What does it form

Answer 5

A noncovalent

Forms a hydrogen bridge

Question 6

What is a van der waals interaction

Answer 6

When the charge isn’t evenly distributed around the molecule (not symmetric)

The partial positive and negative charges interact with each other

Question 7

What is the van der waals contact distance?

Answer 7

The distance between the two molecules where the attraction is greatest

Question 8

What happens when molecules are too close? Too far?(infinity)

Answer 8

Repel if close

No interaction if far (NRG =0)

Question 9

What are ionic interactions

Answer 9

Attraction of oppositely charge ions/ atoms

Question 10

What is meant by a high dielectric constant

Answer 10

Water shielding the separate postive and negative charges of the salt so the the salt can dissolve

Question 11

What is Coulomb’s law

What happens if r or D increases

Answer 11

E=kqq/Dr

D=dielectric constant
R= distance between charges

E decreases

Question 12

What is the hydrophobic effect

Give example

Answer 12

An entropic process where the nonpolar hydrophbic molecules group together to decreases the interaction with water

Can have different combos of chafe, so diff entropy

Ex. Lipid bilayer

Question 13

What type of bond has the highest NRG

Which type of interactions are similar in energy

Answer 13

Covalent: more stable and harder to break

Noncovalent (ionic, h bond, van der)

Question 14

Why are noncovalent interaction weaker

What can they do

Answer 14

Weaker because they allow formation and breakage

The noncovalent interactions can sum up

Question 15

Kw is for

Ka is for

Answer 15

Water

Acid

Question 16

What happens to ph when acid is added to water

What about sodium acetate

What does this mean

Answer 16

Ph imeaditely drops

Ph drops but has a range where it drops more slowly

So sodium acetate acts as a ph buffer between 3.8 and 5.8 ph

Question 17

What are the mono protic acids and their ka

Answer 17

Acetic acid (ka 1.74x10-5)

Ammonium ion (5.62X10-10)

Question 18

What are the di protic acids and their ka

When are the a good buffer

Answer 18

Carbonic acid

Bicarbonate

Glycine, carboxyl (1.3-3.3 ph)

Glycine, amino (8.6-10.6)

Question 19

What are the triprotic acids

Answer 19

Phosphoric acid

Dihydrogen phosphate

Monohydrogen phosphate

Question 20

Why are biological systems buffered

Answer 20

Because if you lose or add a proton to the systems the properties of the system change

Question 21

What is buffer capacity

Answer 21

The max amount of h that can be added until it can’t resist ph change anymore

Question 22

Henderson hassle balch equation

Answer 22

Ph = pka + log (base/acid)

Question 23

In a triphosphate system, which form would be important for buffering a living cell

Answer 23

The one at ph around 7

Question 24

What is a major buffer in blood and what plays a role in the buffering system

Answer 24

Carbonate,

Co2 plays a role in maintaining the Ph at 7.4