Acids, Bases and Buffers

The pH is a measure of the concentration of ______________ _____ in a solution

hydrogen ions

What is 'p' in pH?

mathematical operator that means "negative logarithm of"

pH=

-log[H+]

the difference between hydrogen and hydronium ion is

hydronium ion is the aqueous version

Acid is a substance that ___________________ a proton to a _________________

donates, base

Base is a substance that ___________________ a proton from an __________________

accepts, acid

What is the Bronsted-Lowry theory?

acids are proton donors and bases are proton acceptors

Bronsted-Lowry conjugate base

results when an acid gives up a proton

Bronsted-lowry conjugate acid

results when a base accepts a proton

Water is what on the pH scale?

neutral

Water ionizes into

hydronium (strong acid) and hydroxide ions (strong base)

What is Le Chatelier's principle?

Equilibrium is a good thing! (nature strives for equilibrium)

What are some factors that affect equillibrium?

concentration, temperature and pressure changes, addition of catalyst

HCl is an

acid

When HCL --> H+ + Cl-, proton was ____________, so Cl- is the conjugate _______________

donated, base

HCl is the conjugate ___________ of the base, Cl-, ___________ a proton

acid, accepted

In acid-base reactions, the acid is converted into its ______________ ___________ and the base is converted into its _______________ ____________

conjugate base, conjugate acid

What does amphiprotic mean?

can behave as an acid or a base

What is a common example of an amphiprotic compound?

water &

monohydrogen phosphate

A strong acid _______________ ionizes in water and produces H+

completely

a weak acid ____________ ionizes in water and creates a _________ amount of hydrogen ions

partially, tiny

a strong base is one that dissociates _____________ or to a large extent in water

entirely

weak bases do not _______________ entirely or only dissociate a little

dissolve

What is a buffer?

a substance that minimizes changes in pH

buffers _____________ change in pH

resist

what is a common buffer system in the body?

bicarbonate buffer system

when acids and bases react to neutralize one another _________ is created

salt

What are some other words for ionized?

charged, polar, water soluble, hydrophilic, low lipid solubility, lipophobic

what are some other words for non-ionized?

uncharged, non-polar, lipid soluble, hydrophobic, low water solubility, lipophilic

Do ionized or non-ionized drugs travel around more easily? Why?

non-ionized, due to lipid membrane

Whether acidic or basic, the degree of ionization of an agent at a particular site is determined by the __________ _______________ _____________ of the agent and its pH gradient across the membrane

pKa dissociation constant

Ka=

acid dissociation constant

how much acid/how much conjugate base

p=

negative log 10

pKa=

-log[Ka]

A drugs pKa is the pH when _____________ of the drug is ionized and __________ is non-ionized

50%, 50%

If pKa increases more from pH, what happens to ionization?

increases

The smaller the value of pKa, the ____________ the acid

stronger

pH tells us the __________ or ____________ of a solution

acidity, alkalinity

pKa is a ____________ property of a solution

constant

pKa tells us how much a drug wants to behave like an _____________

acid

What is the Henderson-Hasselbalch equation?

pH = pKa + log [A-]/[HA]

the ideal Henderson-Hasselbach Equation says

pH=pKa

weak bases into basic solution =

pH>pKa

what is ion trapping?

when uncharged molecules can equilibrate across the cell membrane but charged ions can't and get stuck

why does charged ion get trapped?

due to more acidic environment

when is ion trapping an issue?

maternal-fetal transfer, fetus has lower pH, and weak base enters environment and gets trapped

Weak acids are paired with ____ ions such as....

cation

Na+, K+, Mg+

Weak bases are paired with ____ ions such as ...

anion

Cl-, I-, NO_3-