4b: Drug Availability

Question 1

Acids and Bases

Lewis definition of acid & base?

Answer 1

Acid: e- acceptor
Base: e- donor

Question 2

Acids and Bases

Bronsted-Lowry definition of acid & base?

Answer 2

Acid: proton donor
Base: proton acceptor

Question 3

When dissolved in water, ____ acids completely ionize (break apart ions).

Answer 3

Strong Acids.

HCl, HBr, HI, HNO3, HClO4, H2SO4

Have weak conjugate bases.

Question 4

When dissolved in water, ____ acids partially ionize.

Answer 4

Weak acids. (prefers this form)

HF, H2CO3, H3PO4, organic acids (carboxylic acid, protonated drugs, etc)

*Have STRONG conjugate bases.

Question 5

When dissolved in water, ____ bases completely ionize (break apart ions).

Answer 5

Strong bases.

LiOH, NaOH, KOH, Sr(OH)2, Ca(OH)2, Ba(OH)2

Question 6

When dissolved in water, ____ bases partially ionize.

Answer 6

Weak bases.

Mg(OH)2, transition metal hydroxies, NH3

Question 7

When a base accepts a proton, what has it now become?

Answer 7

Conjugate acid!

Question 8

When an acid gives away a proton, what has it now become?

Answer 8

Conjugate base!

Question 9

What is amphoteric?

Answer 9

When speaking of water, it means it can act as either an acid or a base.

She’s a lil indecisive. ;)

Question 10

What is the water constant (Kw)
(pH + pOH = )

Answer 10

14

Question 11

pH is 7. What substance am I most likely describing here?

Answer 11

Pure water! (Neutral pH)

Question 12

Is the pH scale logarithmic? What does this mean?

Answer 12

Yes. This means an increase of 1 (so pH of 6 to 7) is actually a factor of 10!!!

Question 13

How do we measure acid strength? (2 ways)

Answer 13

1. Ka (acid-dissociation constant) (the larger = more acidic = easier it is to remove a proton)
2. pKa (the lower, the more acidic)

Question 14

pKa scale

*lower = more acidic

Answer 14

• -20 - 25 = acidic!
• 30-60 = not as acidic (not considered basic)

Question 15

Strong base calculation ____.

Answer 15

1. pOH- = -log [OH-]
2. pH + pOH = 14 (plug in and solve)

*remember normal range for pH of a base (>7)

*dont forget to balance your equation!!!

Question 16

Strong acid calculation ____.

Answer 16

pH = -log [HCO3]

*dont forget to balance your equation!!!

Question 17

(Ka/Kb x M), take square root, plug into pH or pOH formula accordingly (subtract 14 if Kb/base).

Answer 17

Calculating pH given the Moles & Ka/Kb.

Question 18

Bases produce ____, acids produce ____.

Answer 18

Bases = hydroxide (OH-)
Acids = hydronium (H3O+)

Question 19

What is a homogenous mixture of 2 or more substances?

Answer 19

Solution!

Question 20

Where do most chemical reactions take place?

Answer 20

In water!

*most common and most important

Question 21

What is the major component of a mixture?

Answer 21

Solvent

Question 22

What is the minority component of a mixture?

Answer 22

Solute.

Question 23

What are two terms that could describe the amount of solute in a solution?

It is either ___ or ___.

Answer 23

1. Concentrated
2. Diluted

Question 24

Blood pH calculation

Answer 24

pH = 6.1+ log (HCO3/0.03 x pCO2)

Question 25

Majority of local anesthetics are ___.

This allows them to cross axonal membranes to initiate onset quickly!

Answer 25

• Weak bases
• having a pKa closer to physiological pH will exist in more lipid-solube unionized form.

Question 26

What is buffer capacity?

Answer 26

The limit to the amount of acid/base that can be added before the buffer loses its ability to resist change.

Question 27

What resists change in pH when strong acids or strong bases are added in limited quantity?

Answer 27

Buffers.

Question 28

What are 3 main buffer systems?

Answer 28

1. HCO3
2. phosphate
3. protein

resp = co2 control, renal = H+ control

Question 29

What does a low % ionization mean?

Answer 29

That it is more lipid soluble and can cross membranes easier.