Exam 1: Chp 2

Question 1

What does it mean that water has a fluid network of H-bonds?

Answer 1

The H-bonds within liquid water are constantly breaking and reforming

Question 2

How does water behave in the process of ionic compounds?

Answer 2

Surrounds the ions, breaking them apart, and forming hydration shells
Ions can clump together and form clathrates

Question 3

What is a clathrate?

Answer 3

When molecules of one substance (water) entirely surrounds molecules of another

Question 4

How does water behave in the presence of non polar compounds?

Answer 4

Form clathrates surrounding the non polar molecules, cause non polar molecules to clump together due to hydrophobic effect

Question 5

How does water behave in the presence of amphipathic molecules?

Answer 5

the amphipathic molecules form micelles

Question 6

What are micelles?

Answer 6

A gathering of amphipathic molecules with their hydrophobic parts directed in the center and their hydrophilic pants directed outwards

Question 7

What is the hydrophobic effect?

Answer 7

Nonpolar molecules are pushed together by H2O molecules that are attracted to each other by H-bonds

Question 8

What is the equation for pH?

Answer 8

pH = -log[H+]

Question 9

What is the expression for pKa?

Answer 9

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

Question 10

How is pH and acidity affected when a reaction has a lower pKa than another?

Answer 10

The compound with a lower pKa is more acidic, lower pH → the proton is more likely to be removed by base

Question 11

How is pH and acidity differ when pKa of one compound is higher than another?

Answer 11

The compound with a higher pKa is less acidic, has a higher pH → likely protonated

Question 12

How does electronegativity affect pKa and acidity?

Answer 12

decreases pKa, increases acidity

Question 13

How does resonance affect pKa and acidity?

Answer 13

More resonance stabilization of the conjugate base decreases pKa and increase acidity

Question 14

How does the inductive effect impact pKa and acidity?

Answer 14

Electron withdrawing groups near the acidic proton lower pKa and increase acidity

Question 15

How does hybridization impact pKa and acidity?

Answer 15

More s-character lowers the pKa value and increases acidity

Question 16

What are electron withdrawing groups?

Answer 16

Molecules that are electronegative

Question 17

How does atom size impact pKa and acidity?

Answer 17

A larger atom distribute charge more which lowers the pKa value and increase acidity

Question 18

Is the weak acid or conjugate base the predominant form when pKa < pH?

Answer 18

The conjugate base will predominate (deprotonated form)

Question 19

Is the weak acid or conjugate base the predominant form when pH = pKa?

Answer 19

They are of equal concentrations

Question 20

Is the the weak acid or conjugate base the predominant form when pKa > pH?

Answer 20

The weak acid will predominate (protonated form)

Question 21

What is a buffer?

Answer 21

A solution that resists pH change by neutralizing acids or bases, either consisting of a weak and conjugate base or weak base and conjugate acid

Question 22

What is the pKa of a buffer that works well in physiological conditions?

Answer 22

pKa of 6.4-8.4

Question 23

Why are buffers important for biochemical processes?

Answer 23

The molecules in cells and in the body are sensitive to pH changes and buffers help resist them

Question 24

Wha is the pH of physiological conditions?

Answer 24

Around 7.4

Question 25

Why does carbonic acid buffer work well in the body despite its low pKa?

Answer 25

Because CO2 concentration is constantly regulated by the body for function

Question 26

How does hyperventilation affect carbonic acid buffer concentrations?

Answer 26

CO2 is decreased, decreasing the amount of H+ and bicarbonate → increase pH

Question 27

How does hypoventilation affect carbonic acid buffer concentrations?

Answer 27

CO2 is increased, increasing amount of H+ and bicarbonate → decrease pH