Lecture 3: Acids, Bases, And Buffers Flashcards

1
Q

Most chemical reactions are ___

A

Reversible

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2
Q

What does dynamic equilibrium mean?

A
  • Reactants can combine to give products

- Products can fall apart to give reactants

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3
Q

What does Le Chatelier’s Principle state about equilibrium?

A

When a system in a state of dynamic equilibrium is disturbed, it will react to re-establish the equilibrium condition; nature likes being in an equilibrium state

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4
Q

A system is in a state of equilibrium when there is a…

A

balance between reactants and products

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5
Q

As K increases, the reaction tends to increasingly favor…

A

Products

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6
Q

As K decreases, the reaction tends to increasingly favor…

A

Starting materials (the reverse reaction becomes more favorable)

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7
Q

K subscript a =

A

Weak acids

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8
Q

If you add products, the equilibrium will shift towards…

A

reactants

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9
Q

If you remove products, the equilibrium will shift toward…

A

products

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10
Q

What is Bronstead acids and bases?

A

The most generally useful definition of an acid

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11
Q

An acid is a ___

A

proton (hydrogen ion) donor

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12
Q

A base is a ___

A

proton (hydrogen ion) acceptor

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13
Q

Proton donor =

A

Acid

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14
Q

Proton acceptor =

A

Base

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15
Q

When an acid donates a proton, it is converted into its ___ ___

A

Conjugate base

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16
Q

When a base accepts a proton, it is converted into its ___ ___

A

conjugate acid

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17
Q

What is an amphoteric species (amphiprotic species)? Give an example.

A

Something that can behave as either an acid or a base, i.e.: water

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18
Q

The stronger the acid, the weaker the ___ ___

A

conjugate base

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19
Q

The weaker the acid, the stronger the ___ ___

A

conjugate base

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20
Q

Weak acids do not…

A

Ionize 100% in water

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21
Q

Weak bases establish an equilibrium by…

A

Accepting a proton from water

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22
Q

The pH scale quantitatively describes…

A

The “acidity” or “alkalinity” of a solution

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23
Q

PH 7

A

Neutral

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24
Q

PH < 7

A

Acidic

25
Q

PH > 7

A

Basic

26
Q

A system is in balance (equilibrium) when there is a balance between…

A

the reactants and products

27
Q

What is K?

A

K is the equilibrium constant which provides a numerical description of that balance

28
Q

As K increases, the reaction tends to increasingly favor ___

A

products

29
Q

As K decreases, the reaction tends to favor ___

A

The starting materials

30
Q

PKa is the point at which…

A

50% of a drug is ionized, and 50% of the drug is nonionized

31
Q

A pH buffer is…

A

a solution that resists changes in pH

32
Q

A pH buffer may contain…

A

a weak acid (HA) in its conjugate base

33
Q

When the concentration of a weak-acid and its conjugate base are equal, the ___ is equal to the ___

A

pH is equal to the pKa

34
Q

When is the pH equal to the pKa?

A

When the concentration of a weak-acid and its conjugate base are equal

35
Q

Drug utilization by the body is determined by…

A

the degree of ionization/non ionization

36
Q

Non ionized drug is…

A

lipid soluble and readily penetrates the blood brain and placental barriers

37
Q

Lipid soluble =

A

non water soluble = hydrophobic

38
Q

The ionized form of a drug is…

A

water soluble (hydrophilic)

39
Q

What determines drug effectiveness?

A

Knowing the degree of ionization or non ionization

40
Q

What are 3 steps to determine ionization?

A
  1. Is the drug a weak acid or a weak base?
  2. What is the pKa of the drug? (This is your reference point)
  3. What is the pH of the target solution that the drug is being placed in? (Usually the body where the pH is 7.4).
41
Q

Weak acids become more ___ as pH falls (H+ increases)

A

more nonionized

acid + acid = nonionized

42
Q

Weak acids unite with ___ charged ions such as…

A

positively charged

I.e.: Na+, Mg++, Ca++

43
Q

So, if you see a salt drug (i.e.: sodium drug, calcium drug, magnesium drug), you would recognize the drug as…

A

the salt base form of a weak acid (i.e.: sodium pentobarbital is a salt of a weak acid)

44
Q

Weak bases become more ___ as pH increases (H+ decreases)

A

more nonionized

Base + base = nonionized

45
Q

Weak bases unite with ___ charged ions

A

Negatively

46
Q

If you see salts: i.e.: “drug” chloride, “drug” sulfate, recognize them as…

A

the salt form of a weak base (i.e.: Lidocaine hydrochloride and morphine sulfate are salts of weak bases)

47
Q

Sodium drug, calcium drug, magnesium drug =

A

Salt form of weak acids

48
Q

“drug” chloride, “drug” sulfate =

A

Salt form of weak bases

49
Q

What is the pKa of a weak acid or weak base?

A

The pKa of a weak acid or weak base is the pH at which 50% is ionized and 50% is nonionized

50
Q

The nonionized form of a weak acid =

A

the acid

51
Q

The ionized form of a weak acid =

A

Conjugate base

52
Q

The nonionized form of a weak base =

A

The base

53
Q

The ionized form of a weak base =

A

Conjugate acid

54
Q

The nonionized drug of weak acids penetrates…

A

the blood brain barrier and placental barrier

55
Q

The greater the nonionized portion of the drug, the greater the transfer to…

A

brain and fetus (ion trapping in fetus)

56
Q

What are 3 examples of weak acid drugs?

A
  • Thiopental
  • Barbiturates
  • PROPOFOL***
57
Q

What are 3 examples of weak base drugs?

A
  • Lidocaine (locals)
  • Morphine (opioids)
  • Versed (benzos)
58
Q

What happens to local anesthetics in fetal circulation?

A

-Trapping of local anesthetics in fetal circulation

59
Q

Why does ion trapping occur in fetal circulation?

A

The pH of the fetus is lower than maternal, so the circulating nonionized drug crosses the placental barrier