chapter 9 Acid base Flashcards
What is the pH scale based off of?
self-ionization of water
what is the equation that defines pH?
pH=-log[H+]
What is the pH of neutral, acidic, and basic solutions?
pH of 7 is neutral
below 7 is acidic
above 7 is basic
Chemical substance that donates a H+ is known as?
Acid
Chemical substance that accepts a H+?
Base
Proton donor is known as?
an acid
Proton acceptor is known as?
Base
Examples of strong acids?
HCl, H2SO4, HNO3
Examples of strong Bases?
NaOH, KOH, Ca(OH)2
what is the main difference in defining a strong acid or base from a weak acid or base?
Strong acids or bases will completely dissociate (100%) in water.
Weak acid or base will only partially dissociate in water.
what does A- stand for?
ionized form of an acid
what does HA stand for?
non-ionized form of an acid
what does BH+ stand for?
ionized form of a base
what does B stand for?
non ionized form of a base
what form of an acid or base can pass through the lipid bi layer?
non-ionized form of an acid or base
what form of an acid or base can NOT pass through a lipid bi layer?
ionized form
List 6 common weak acids that are medications.
Thiopental Barbiturates Phenobarbital Methotrexate TCAs Aspirin
List 4 common weak bases that are medications.
Local anesthetics: Lidocaine
Amphetamine
Morphine
Most drugs are either weak acids or bases or strong acids or bases?
most drugs are weak acids and weak bases.
Do you want a drug which is stored for use in an ionized or non ionized form?
ionized, this equals water solubility and you can control the drug more in this form.
HA represents what kind of drug?
Acidic drug
if an acidic drug (HA) releases a proton (H+) what will it then cause to form?
anion (A-) to form
B represents what kind of drug?
Basic drug
if a basic drug (B) accepts a proton (H+) what does it then cause to form?
cation (BH+) to form
is the ionized charged form or a drug water or lipid soluble?
water soluble
what type of drug can cross the lipid bi layer, water or lipid soluble?
lipid soluble can cross the bi layer, that would also be non- ionized form of a drug.
match the following terms to one another.
water soluble
non ionized form
lipid soluble
ionized form
ionized form = water soluble
non ionized form= lipid soluble
another way to say lipid soluble is to say?
water insoluble
if something is water insoluble what does that mean in relation to crossing the cell membrane?
water insoluble means it CAN cross the cell membrane because it is lipid soluble.
if a drug is lipid insoluble what does that mean?
lipid insoluble means water soluble and thus it can NOT cross the cell membrane.
Degree of ionization of a drug depends on two things?
pH and pKa
the environment in which the drug is present is known as the?
pH
ionization constant of the drug is known as?
pKa
When pH < pKa?
increased HA and BH+ predominate.
When pH > pKa?
increased A- and B predominate.
Distribution of a drug between its ionized and non-ionized forms depends on the?
pH and pKa
the pH at which 50% of drug is ionized and 50% in non-ionized is known as what?
pKa
When pH = pKa what else is = to one another?
HA=A- and
BH+ = B
Acidic drug + acidic media yields?
Non-ionized form (lipid soluble)
Acidic drug + basic media yields?
Ionized form (water soluble)
Basic drug + basic media yields?
Non-ionized form (lipid soluble)
Basic drug + acidic media yields?
Ionized form (water soluble)
When the pH of a weak acid increases, it then becomes more what?
It is moving towards alkaline, thus becoming more ionized.
When the pH of a weak acid decreases, it becomes more what?
if the pH is decreasing then it is becoming more acidic, and since it is already a weak acid it will become more non-ionized (which means more lipid soluble)
Ionized form of any drug is more soluble in water or lipids?
ionized = water soluble
With a weak acid, as the pH increases what happens to the solubility?
the solubility (water solubility) increases
with a weak acid as the solubility decreases what direction would the pH be moving?
the pH would be decreasing to decrease the solubility
in regards to a weak acid is solubility and pH proportional or inversely proportional?
pH and solubility are directly proportional with weak acids.
would a weak acid be mixed and stored in a high pH or low pH solution?
high pH solution (basic) in order to render the drug more neutral, ionic, water soluble.
No precipitate will form.
Weak base, what pH solution would you mix it with to make it more non ionized?
a higher pH solution. It is already a base, thus mixing it with a more alkaline solution will make the drug more non-ionized = lipid solubility.