Acid Base

Question 1

Water Electron Shell

Answer 1

Electron shell: inner shell has two valence electrons, outer shell has 6 –> always wants outermost shell full so combines with H+ (covalently bonded bc share electrons)

Question 2

Principle Chemistry of Water

Answer 2

• Simple triatomic molecule
• Molecules in constant motion –> Brownian motion
• Attract each other, form hydrogen bonds
• Occasional proton (H+) transfer when collision occurs, resulting in hydronium ion (H3O+) or some relative (H9O4+)
• Key = transfer of positive charge
• Partially negative at O end due to lone electron pairs, partially positive at H end

Question 3

Water Molecule Anatomy

Answer 3

Distance btw O and H is 95.84 picomoles
Angle btw two hydrogen molecules is 104.45* - should be 109* but H molecules pushed closer together by lone electron pair

Question 4

1 mole

Answer 4

6.023 x 10^23 particles

Question 5

H20 Dissociation

Answer 5

Slightly dissociates into H and OH (hydroxyl) ions
This tendency to dissociate is described by:
Keq x [H20] = [H+] x [OH-] @ 25C
**Concentrations of each ion only 1 x 10^-7 mmol/L (M) @ 25*C or 1x10^-14 M total ions

Question 6

Molarity of pure water (neutral)

Answer 6

55.5M

[H] = [OH]

Question 7

Water Dissociation Constant (Kw’)

Answer 7

Keq x [H20] = Keq x 55.5M = Kw’
Kw’ = [H+] x [OH-] = 1 x 10^-14
Kw’ dictates the relative concentration of [H] and [OH] are constant

Question 8

Acidic Solution

Answer 8

[H+] > 1 x 10^-7M

Question 9

Basic Solution

Answer 9

[OH-] > 1 x 10^-7M

Question 10

If H+ is 1.0M, what is OH?

Answer 10

OH = 1.0 x 10^-14 –> acidic solution

Question 11

If H+ is 1.0 x 10^-3M, what is OH?

Answer 11

OH = 1.0 x 10^-11 –> acidic solution

Question 12

If H+ is 1.0 x 10^-7M, what is OH?

Answer 12

OH = 1.0 x 10^-7 –> pure water

Question 13

If H+ is 1.0 x 10^-10M, what is OH?

Answer 13

OH = 1.0 x 10^-4 –> basic solution

Question 14

If H+ is 1.0 x 10^-14M, what is OH?

Answer 14

OH = 1.0M –> basic solution

Question 15

If OH- is 1.0 x 10^-14M, what is H+?

Answer 15

H = 1.0M –> acidic solution

Question 16

If OH- is 1.0 x 10^-11M, what is H+?

Answer 16

H = 1.0 x 10^-3M –> acidic solution

Question 17

If OH- is 1.0 x 10^-4M, what is H+?

Answer 17

H = 1.0 x 10^-11M –> basic solution

Question 18

If OH- is 1.0M, what is H+?

Answer 18

H = 1.0 x 10^-14M –> basic solution

Question 19

Arrhenius Acid

Answer 19

Any substance that delivers an H+ into an aqueous solution

• In an aqueous solution: H20 + H+ –> H3O+
• Or: HCl + H20 –> H3O+ + Cl-

Question 20

Arrhenius Base

Answer 20

Any substance that delivers an OH into an aqueous solution

-In an aqueous solution: NaOH + H3O+ –> Na + 2H20

Question 21

H20, Acid-Base Dissociation

Answer 21

H20 = highly ionizing –> substances with polar bonds dissociate well in it

• Degree of ionization determines whether an ion is strong
• Strong ions completely dissociate –> free in solution
• Weak acids/bases ionize only partially

Question 22

Examples of Arrhenius Acids

Answer 22

Cl-, Lactate-, ketones-, sulfate-, formate

Cause retention of H+ to maintain electroneutrality

Question 23

Examples of Arrhenius Bases

Answer 23

Na+, K+, Ca2+, Mg2+

Cause retention of OH- to maintain electroneutrality

Question 24

Bronsted-Lowry Acids and Bases

Answer 24

Expanded definition of AB in 1923
Not all bases have hydroxyl group (OH)
Ex: NH3, NaCO3

Question 25

Bronsted-Lowry Acid

Answer 25

Any substance capable of donating H+

Must have H+ in its structure

Question 26

Bronsted-Lowry Base

Answer 26

Any substance capable of accepting H+

Question 27

Water and BL AB

Answer 27

Water = amphoteric –> can act as a BL acid and a BL base

Question 28

Conjugate Base of a BL Acid

Answer 28

Substance formed after acid donates H+
HA + B –> A- + BH+
A- = conjugate base
BH+ = conjugate acid

Question 29

Conjugate Acid of a BL Base

Answer 29

Substance formed after base accepts H
HA + B –> A- + BH+
A- = conjugate base
BH+ = conjugate acid

Question 30

Hydrogen Ions

Answer 30

Important electrolytes (Na, Mg, K) are measured in mEq/L but H+ measured in nEq/L
Why H+ problematic:
- Very reactive
- Proteins have dissociable groups that gain/lose H+ if {h} changes, affecting structure and function

Question 31

[H] compatible with life

Answer 31

16-160 nEq/L

Question 32

What concentration of [H+] corresponds to a pH of 7.4?

Answer 32

Normal [H+] @ pH = 7.4 = 40nEq/L
= 0.0000004 Eq/L
= 4 x 10^-8 Eq/L

Question 33

What pH range is compatible with life and what hydrogen concentration correlates with those pHs?

Answer 33

pH makes it seem as though [H+] more tightly controlled than it is
pH range compatible with life: 6.9-7.5
[H+] 32-125 nEq/L

Question 34

Law of Mass Action

Answer 34

rate of a chemical reaction is directly proportional to the product of activities/concentration of the reactants

Question 35

Write the derivation of the law of mass action

Answer 35

ADD PICTURE

Question 36

Ka

Answer 36

Ionization/dissociation constant
Larger Ka = Larger K1 = stronger acid –> more [H+], [A-], and more dissociation
Smaller Ka = Larger K2 = weaker acid –> more [HA], less dissociation
Directly proportional to temp: increased T –> increased Ka –> increased dissociation

Question 37

Draw the derivation of the Henderson-Hasselbach equation

Answer 37

ADD PICTURE

Question 38

Henderson-Hasselbach

Answer 38

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

Question 39

If pH is lower in the ECF…

Answer 39

meaning that the [H+] is higher than the pKa, then the compound will be protonated ie the more protonated compound will exist more than the unprotonated/dissociated compound

Question 40

If pH is higher in the ECF…

Answer 40

meaning that the [H+] is lower than the pKa, then the compound will be deprotonated

Question 41

Le Chatelier’s Principle

Answer 41

AKA Equilibrium Law or Chatelier’s Principle
-When a system experiences a disturbance (ie concentration, temperature, pressure changes, etc) will respond to a new equilibrium state