Chm 116 Exam 2

Front 1

What is an Arrhenius acid?

Back 1

a substance that increases the concentration of H+ ions in water (i.e. HA)

Front 2

What is an Arrhenius base?

Back 2

a substance that increases the concentration of OH- ions in water (i.e. MOH)

Front 3

What is the common ion effect?

Back 3

the shift in equilibrium caused by the addition of a compound having an ion in common with the dissolved substance

Front 4

What does the pressence of a common ion do?

Back 4

suppresses the ionization of a
weak acid or a weak base

Front 5

What is a Bronsted acid?

Back 5

a proton (H+) donor

Front 6

What is a Bronsted base?

Back 6

a proton (H+) acceptor (if it's strong it could be aka a proton "grabber")

Front 7

What ability does a buffer solution have?

Back 7

to resist changes in pH upon the addition of small amounts of either acid or base (so the change in pH, relative to an un-buffered solution is slight)

Front 8

What is a buffer solution composed of?

Back 8

a weak acid and a salt containing the conjugate base
OR
a weak base and a salt containing the conjugate acid
OR
a weak acid/base and an appropriate amount of a strong base/acid (like HCl)

Front 9

True or False? A base will not have unpaired (lone pair) electrons.

Back 9

False

Front 10

What charges can a base have?

Back 10

neutral or negative

Front 11

How much of a strong acid protonates (transfers protons to) a weak base?

Back 11

100%

Front 12

What does every Bronsted acid/base have?

Back 12

a conjugate base/acid

Front 13

What are conjugate acid-base pairs?

Back 13

chemical species whose formulas differ only by one proton

Front 14

What can an amphiprotic substance do?

Back 14

act as either a proton donor or proton acceptor

Front 15

How do strong and weak electrolytes dissociate?

Back 15

strong = 100% dissociation
weak = not completely dissociated

Front 16

What are the 6 strong acids that were asked to be memorized?

Back 16

HCl, HBr, HI, HNO3, HClO4, H2SO4 (only the first proton is considered strong)

Front 17

True or False? Bases with alkali or alkaline earth metals are strong.

Back 17

True

Front 18

How strong of electrolytes are weak and strong acids/bases?

Back 18

weak acids/bases = weak electrolytes
strong acids/bases = strong electrolytes

Front 19

Where does the equilibrium lie/predominate in any acid-base pairing?

Back 19

with the weaker acid and weaker base

Front 20

True or False? The weak acid is always paired with the weak base and that the strong acid is always paired with the strong base.

Back 20

True (so once you know one, you will know the others)

Front 21

True or False? Strength of an acid/base is the same as concentration.

Back 21

FALSE

Front 22

What is the strongest acid that can exist in aqueous solution?

Back 22

H3O+

Front 23

What is the strongest base that can exist in aqueous solution?

Back 23

OH-

Front 24

What is the ion-product constant?

Back 24

(Kw) = the product of the molar concentrations of H3 O+ and OH- ions at a particular temperature (at 25 degrees C = 1.0 * 10^-14)

Front 25

What are the formulas for pH and pOH and what do they add to?

Back 25

pH = -log[H+]
pOH = -log[OH-]
pH + pOH = 14

Front 26

How do you find [H+] / [OH-] if given pH / pOH?

Back 26

[H+] = 10^-pH
[OH-] = 10^-pOH

Front 27

True or False? Each number increase/decrease on the pH sale represents a 10-fold increase/decrease.

Back 27

True

Front 28

As Ka (the acid-dissociation/ionization constant) increases, what happens to pKa and weak acid strength?

Back 28

pKa decreases and weak acid strength increases

Front 29

What is the % ionization formula?

Back 29

( [H+] at equilibrium / initial [acid] ) * 100%

Front 30

What happens to % ionization as weak acid is diluted with water?

Back 30

it increases

Front 31

What happens to weak base strength as Kb (the base ionization constant) increases?

Back 31

it increases

Front 32

What does Kw equal in relation to Ka and Kb for weak acids/bases and their conjugates?

Back 32

Kw = Ka * Kb

Front 33

What affects pH (cation or anion) for neutral, acidic, and basic solutions?

Back 33

Neutral Solutions – The cation and anion do not affect pH.
Basic Solutions: – The anion affects pH.
Acidic Solutions: – The cation affects pH.

Front 34

What is the Inductive Effect?

Back 34

“Movement or withdrawal” of electrons from neighboring bonds by either electronegative atoms or positive-charged atoms.

Front 35

When is the solution basic, acidic, and neutral for solutions in which the cation AND anion affect pH?

Back 35

Basic: Kb for the anion > Ka for the cation
Acidic: Kb for the anion < Ka for the cation
Neutral: Kb for the anion ≈ Ka for the cation

Front 36

What 3 factors does the acidity of hydrogen (the ease in which the proton dissociates from the molecule) depend on when hydrogen is bonded to another element?

Back 36

H-X bond strength, H-X bond polarity, & the stability of the conjugate base (X−) (high stability = no base activity)

Front 37

When does acidity increase for binary acids?

Back 37

from left to right across a row (H-X bond polarity increases) AND from top to bottom down a group (H-X bond strength decreases)

Front 38

When will the O-H bond be more polar and easier to break?

Back 38

If Z is very electronegative or Z is in a high oxidation state (more oxygens bonded to it).

Front 39

When does acid strength increase for oxyacids?

Back 39

with increasing electronegativity and oxidation #'s of Z

Front 40

What is a Lewis acid?

Back 40

a substance that can accept a pair of electrons

Front 41

What is a Lewis base?

Back 41

a substance that can donate a pair of electrons

Front 42

What happens to a buffer solution when a strong acid/base is added?

Back 42

Strong acid: excess protons are neutralized by the weak base
Strong base: excess hydroxide ions are neutralized by the weak acid

Front 43

What is the Henderson-Hasselbalch equation?

Back 43

pH = pKa + log( [conjugate base]/[acid] )

Front 44

What is buffer capacity?

Back 44

the amount of acid or base neutralized by the buffer before there is a significant change in pH

Front 45

True or False? The greater the amounts of conjugate acid-base pair, the greater the buffer capacity.

Back 45

True

Front 46

What happens to a buffer solution when a strong acid/ base is added?

Back 46

Strong acid: weak acid increases, weak base decreases
Strong base: weak base increases, weak acid deceases

Front 47

When is the reaction complete in an acid-base titration?

Back 47

at the equivalence point

Front 48

What is equal at the equivalence point?

Back 48

mol acid = mol base

Front 49

In a strong acid-strong base titration, what is the relationship between [H+] and [OH-] before and after equivalence point?

Back 49

Before the equivalence point: [H+] > [OH−]
After the equivalence point: [H+] < [OH−]

Front 50

What is the pH at the equivalence point in a weak acid-strong base titration?

Back 50

pH > 7

Front 51

What is equal at the "half-way equivalence point?

Back 51

[A-] = [HA]

Front 52

True or False? Ionic Compounds are infinitively soluble in water.

Back 52

False

Front 53

What is the Solubility Product Constant (Ksp)?

Back 53

the product of the molar concentrations of constituent ions IN A SATURATED SOLUTION raised to their stoichiometirc powers (it provides a measure of a compound’s solubility)

Front 54

What is molar solubility?

Back 54

the number of moles of solute dissolving to form a liter of saturated solution (in M) (it refers to the “parent” compound)

Front 55

What is solubility?

Back 55

the amount (grams) of substance that dissolves to form saturated solution (in g/L)

Front 56

What does the presence of a common ion do to the solubility of a salt?

Back 56

it decreases it

Front 57

What happens to the solubility of "insoluble" bases in acidic solutions?

Back 57

it increases

Front 58

What is the relationship between Ksp and Q for unsaturated, saturated, and supersaturated solutions?

Back 58

Ksp > Q for Unsaturated
Ksp = Q for Saturated
Ksp < Q for Supersaturated (precipitate forms)