Acids/bases

Front 1

Polar

Back 1

charged/ionized

Front 2

Nonpolar

Back 2

noncharged/ nonionized

Front 3

ionized molecules

Back 3

do not readily or rapidly cross membranes
-ionized molecules are water soluble

Front 4

nonionized (neutral)molecules

Back 4

do readily and rapidly cross membranes, "like dissolves like"
-nonionized molecules are lipid soluble

Front 5

acids

Back 5

taste sour, dissolve some metals, turn litmus pink

Front 6

bases

Back 6

taste bitter, feel slippery and soapy, turn litmus blue

Front 7

Arrhenius Theory

Back 7

-acids produce H+ in water
-bases produce OH- in water

-definition was limited so it was changed in 1920

Front 8

Bronsted-Lowry Theory of Acids

Back 8

-acid is a proton donor (becomes nonprotonated)
-becomes net negative charge = ionized

Front 9

Bronsted-Lowry Theory of
base

Back 9

-Base is a proton acceptor (becomes protonated)
-becomes net positive charge = ionized

Front 10

Dissociation

Back 10

the loss or gain of a proton

Front 11

How about the human body?

Back 11

Bronsted-Lowry hold true since the human body is 70-75% water it is a safe assumption that most molecules are in low [], therefore the body behaves as a dilute soln

Front 12

H+

Back 12

Short hand for H30+

Front 13

Example: Acid

Back 13

HCN + H20 <> CN- + H+

Front 14

Example: Base

Back 14

NH3 + H20 <> NH4+ + OH-

Front 15

Amphiprotic/Amphoteric

Back 15

Water may behave as either an acid or a base

Front 16

Conjugate acid

Back 16

is the species formed when a base accepts a proton

Front 17

conjugate base

Back 17

is the species formed when an acid donates a proton

Front 18

conjugate acid-base pair

Back 18

the acid and base on te opposite sides of the equation

Front 19

strength of and acid or base

Back 19

-is not the concentration!
-is a measure of the degree of dissociation of the substance in a soln.
-classified as stong when the rxn with h20 is 100% complete
-strong acids/bases completely dissociate whereas weak ones never dissociate completly

Front 20

How can you tell if its a strong acid/base by looking at the rxn?

Back 20

typicall the dissociation of a strong acid/base is shown with a single forward arrow, indicating little tendency to reverse direction to establish equilibrium

Front 21

What do we have in the body?

Back 21

because we are always dealing with a dilute aqueous soln in the body the strongest base that can be present is OH- and the strongest acid is H30+

Front 22

Strong acid example

Back 22

HCL + H20 > H30+ + Cl-

Front 23

Weak acid example

Back 23

H2CO3 + H20 <> H30+ + HCO3-

Front 24

pKa

Back 24

indicates the relative strength of organic functional groups and allows one to calculate, for a given pH, exactly how much of a molecule is in the ionized and nonionized forms

Front 25

acidity constant

Back 25

equilibrium contant for acid/base expressed as Ka for both

Front 26

How do we get a small value for Ka?

Back 26

if the denominator of the expression is much larger than the numerator
(products divided by reactants)

Front 27

How do we get a big value for Ka?

Back 27

if the numerator of the expression is much larger than the numerator
(products divided by the reactants)

Front 28

How will you determine whether an acid or base is a strong or weak acid/base given the Ka?

Back 28

Ka > 1 implies more product = more dissociation = stronger acid

Front 29

Reverible rxn between H20 & CO2 to form H2C03

Back 29

CO2(g) + H20(l) <carbonic anhydrase> H2CO3(aq)

Front 30

Carbonic acid undergoes spontaneous dissociation, no enzyme just thermal energy

Back 30

H2C03(aq) + H20(l)<>HCO3-(aq) +H30+(aq)

Front 31

The amphiprotic nature of water

Back 31

-water can act as either and acid or base
-the amphiprotic nature of water extends to the interaction of water with itself

Front 32

Important pH concepts

Back 32

-the pH of a 1 M solution of any strong acid is 0
-the pH of a 1 M solution of any strong base is 14
-the pH of a neutral solution is 7.0. "neutral" implies [H30+] = [OH-]

Front 33

decreased [acid]=

Back 33

increased the pH

Front 34

increase [acid]=

Back 34

decreased pH

Front 35

Neutralization

Back 35

-takes place when an acid and base react to form salt and water.
-the term "neutralization" comes from the fact that if proper amounts of acid and bases are combines, they will cancel one another to produce a neutral solution

Front 36

Buffer

Back 36

-a solution that resists change in pH when small amounts of acid or base are added

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The basis of buffer action

Back 37

is the establishment of equilibrium between either a weak acid and its conjugate base or a weak base and its conjugate acid

Front 38

Denniston example of a buffer reaction

Back 38

CH3COOH + H20 <> H30+ + CH300-
weak acid conjbase

Front 39

Addition of a Base (OH-) to a buffer solution

Back 39

-OH- from the base reacts with H30+ producing water
-molecular acetic acid dissociates to replace the H30+ consumed by the base maintaining the pH close to the initial level

Front 40

Addition of H30+ to a buffer solution

Back 40

-H30+ from the acid increases the overall [H30+]
-the system reacts to this stress in accordance with LeChatelier's principle to form more molecular acedic acid; the acetate ion combines with H3O+. Thus the [H30+] and therefore the pH remain close to the initial level

Front 41

Most bilogical buffer systems...

Back 41

consist of weak acids and their conjugate bases

Front 42

Major buffer in the blood: carbonic acid and bicarb ion

Back 42

H2CO3(aq) + H20(l) <>HCO3-(aq) + H30+(aq)

Front 43

Ka for previous buffer system

Back 43

Ka=[HCO3-][H30+]/[H2CO3]

Front 44

Henderson-Hasselbalch equation

Back 44

combination of the equilibrium-constant and the pH