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Chem 1220 > Chpt 16: Acid Base Chemical Equilibria > Flashcards

Chpt 16: Acid Base Chemical Equilibria Flashcards

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1
Q

How should you find the pH if you’re mixing 2 different weak acids, where one acid is way weaker than the other?

A

Do the ICE table for the stronger of the two weak acids.

the weaker acid’s [H+] won’t contribute much to the overall pH

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2
Q

Why does conjugate resonance impact the strength of carboxylic acids?

A

if the conjugate (which an an anion) is stable 2o to its resonance, it is not likely to reclaim H+ to become an acid

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3
Q

what does pH + pOH equal?

A

14

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4
Q

One of the types of weak bases is neutral structures with unpaired e-. What are the two kinds of neutral structures with unpaired e-?

A

NH3 and amines

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5
Q

what is the expression for “Ka” ?

A

[H+][A-]/[HA]

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6
Q

what does Kw equal at room temperature?

A

1.0E-14

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7
Q

what does [H+][OH-] equal?

A

1.0E-14

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8
Q

how does bond strength generally impact the strength of an acid/base

A

stronger bond, weaker acid/base

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9
Q

True or false: when comparing the strength of weak bases, the more negative the base’s charge, the more attractive it is to H+

A

True; More negative, more ability to accept H+

exp. HCO3^- is a weaker base than CO3^2-

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10
Q

what are salts?

A

ionic compounds that make ions in solution

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11
Q

what is an amine?

A

type of weak bases:

characterized as a neutral substance with a nitrogen that has an unbound electron pair for accepting H+

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12
Q

how does conjugate stability generally impact the strength of an acid or base?

A

the more stable the conjugate, the more stronger the acid/base?

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13
Q

How do oxyacids’ strength trend as more terminal oxygens are added?

A

more terminal oxygens, stronger acid (because polarity goes up as oxygens are added)

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14
Q

true or false: if an acid/base is a Lewis acid/base, it must also be a BL acid/based and a Arrhenius acid/base

A

false. (because Lewis acids/bases’ definition does not depend upon H+ involvement like the BL and Arrhenius definitions do)

Lewis is the most general of all the definitions

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15
Q

true or false: in the case of oxyacids, the more terminal oxygens around central atom, the stronger the acid?

A

true

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16
Q

what would happen if you forgot the - sign while trying to go from pH to [H+] using your elementary school calculator

A

it would give you the wrong answer

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17
Q

what is an oxyacid?

A

A molecule in which a central atom is surrounded by terminal atoms (sometimes terminal oxygens), including an OH- group or groups

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18
Q

how does atomic radii generally impact bond strength?

A

bigger radii, weaker bond

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19
Q

If you’re mixing a weak acid and a weak base, how can you tell whether the pH will be acidic or basic?

A

The component with the larger Keq will be the one that determines the pH

Exp.if Ka is bigger than kb, the solution will be acidic

20
Q

what is the expression for “Kw” (in terms of ka and kb)?

A

ka * kb = kw

21
Q

what does the “Kw” k constant represent?

A

the autoionization of water

22
Q

how are Lewis acids defined?

A

as electron pair acceptors

23
Q

what are binary acids?

A

acids that only have two kinds of atoms in them

24
Q

how are Lewis bases defined?

A

as electron donors

25
Q

true or false: the stronger the acid, the weaker the base

A

true

26
Q

what does the “Ka” k constant represent?

A

ratio of ions to acid molecules

27
Q

when do you have to bother with ICE tables: with strong acids/bases or weak acids/bases?

A

waek

28
Q

how do you go from [H+] to pH?

A

take the -log of [H+]

29
Q

what are the two types of weak bases?

A

neutral structures (that have unpaired e- for accepting H+)

charged structures (that are conjugates of weak acids)

30
Q

true or false: if an acid/base is a BL acid/based or a Arrhenius acid/base, it must also be a Lewis acid/base

A

true

31
Q

in a chemical reaction, how can you tell which component acts as a Lewis BASE

A

it will give its unpaired electrons to something else

exp. if Fe(ClO4)3 + 6H2O makes Fe(H2O)6 + 3ClO4^1, H2O gave its unpaired electrons to Fe^3+, and is thus acting as a base

32
Q

how does bond strength trend on the periodic table?

A

strength goes up as you go up the periodic table

33
Q

in a chemical reaction, how can you tell which component acts as a Lewis acid

A

it will accept/receive something else’s electron pair

exp. if Fe(ClO4)3 + 6H2O makes Fe(H2O)6 + 3ClO4^1, the Fe receives the unpaired electrons that H2O had, and is thus acting as an acid

34
Q

in ka or kb problems, when can you ignore the x in the denominator?

A

when the acid or base concentration decreases by less than 5% in order to achieve equilibrium

and/or

when your final acid or base concentration is 5% or less of the original concentration

35
Q

When comparing weak acid or base strength, what can you consider in addition to polarity, bond strength, and stability of the acid’s/base’s conjugate?

A

the ka or kb values involved

36
Q

what does a large ka mean?

A

large ionization; strong acid

37
Q

how does binary acid strength trend as you go across the periodic table?

A

acid gets stronger as you go to the right (bc polarity increases)

38
Q

what is the expression for “Kw” (in terms of H+ and OH- concentrations)?

A

kw = [H+][OH-]

39
Q

how do you go from pH to [H+] using your elementary school calculator?

A

2nd, LOG, -, [pH]

you have to remember the - sign!!!

40
Q

true or false: in the case of oxyacids, the more electronegative the central atom, the stronger the acid?

A

true

41
Q

How do oxyacids’ strength trend as the OXIDATION NUMBER of their central atom increases?

A

higher the oxi number, stronger the acid

42
Q

How do oxyacids’ strength trend as the electronegativity of their central atom increases?

A

acid gets stronger as electronegativity of the central atom goes up

43
Q

How should you find the pH if you’re mixing 2 different weak acids, where both acids are equally weak?

A

Do the ICE table for both, find the [H+] for both, add the two [H+] values together, and use that to calculate the pH

44
Q

how does binary acid strength trend as you go up the periodic table?

A

acid gets stronger as you go down the table (bc bond strength gets weaker as radius increases)

45
Q

how does polarity generally impact the strength of an acid or base?

A

bigger dipole, strong acid/base

Chem 1220 (9 decks)

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