ch 10 - Acids and Bases Flashcards

1
Q

Arrhenius acid

A

dissociates to form an excess of H+ in solution

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2
Q

Arrhenius base

A

dissociates to form an excess of OH- in solution

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3
Q

Bronsted-Lowry acid

A

species that donates a hydrogen ion (H+)

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4
Q

Bronsted-Lowry base

A

species that accepts hydrogen ion (H+)

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5
Q

conjugate acid-base pairs

A

Bronsted-Lowry acids and bases occur in pairs becaues the definitions require transfer of a proton from the acid to the base

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6
Q

Lewis acid

A

an electron pair acceptor

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7
Q

Lewis base

A

an electron pair donor

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8
Q

other terms for Lewis acid-base chemistry

A

coordinate covalent bond formation; complex ion formation; nucleophile-electrophile interactions

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9
Q

amphoteric

A

species that reacts like an acid in a base environment and like a base in an acidic environment

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10
Q

amphprotic

A

a species that can either gain or lose a proton (Bronsted-Lowry)

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11
Q

anion acid nomenclature

A

acids formed from anions with names that end in -ide have the prefix hydro- and the ending -ic: F- (fluoride) = HF (Hydrofluoric acid); Cl- (Chloride) = HCl (hydrochloric acid); Br- (bromide) = HBr (hydrobromic acid)

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12
Q

naming oxyacids

A

oxyacids are acids formed from oxyanions; if anion ends in -ite (less oxygen), acid will end with -ous acid; if it ends in -ate (more oxygen), acid will end with -ic acid and prefixes of names are retained

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13
Q

autoionization

A

water reacted with itself: H20 (l) + H20 (l) ->

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14
Q

water dissociation constant (K sub w)

A

Kw = [H3O+][OH-] = 10^-14 at 25 degrees C (298 K); at temps above this, Kw will increase as a result of the endothermic nature of the autoionization reaction

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15
Q

p scale

A

negative logarithm of the number of items: pH and pOH are prototypical examples

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16
Q

pH

A

-log[H+] = log (1/[H+])

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17
Q

pOH

A

-log[OH-] = log (1/[OH-]

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18
Q

pH and pOH for aqueous solutions at 298K

A

pH + pOH = 14; water at equilibrium and 25 degrees C has a concentration of hydroxide ions (10^-7) = to concentration of hydrogen ions: pH of 7 and pOH of 7

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19
Q

how to multiply logs

A

log (xy) = log x + log y

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20
Q

shortcut to determine p scale values

A

if the nonlog value is written in proper scientific notation, it will be in the form n x 10^-m where n = number between 1 and 10: -log(n x 10^-m) = -log (n) - log(10^-m) = m - log(n); n will equal number between 1 and 10 which means log n will be a number between 0 and 1 (closer to 1 = closer to 0; closer to 10 = closer to 1) so p value = about m - 0.n where 0.n represents sliding the decimal point of n one position to the left

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21
Q

strong acids and bases

A

species that completely dissociate into their component ions in aqueous solutions

22
Q

common strong acids to know

A

HCl (hydrochloric acid); HBr (hydrobromic acid); HI (hydroiodic acid); H2SO4 (sulfuric acid); HNO3 (nitric acid); HClO4 (perchloric acid)

23
Q

common strong bases to know

A

NaOH (sodium hydroxide); KOH (potassium hydroxide); other soluble hydroxides of Group IA metals

24
Q

weak monoprotic acid dissociation in water

A

HA (aq) + H2O (l) ->

25
Q

acid dissociation constant (Ka) of weak acids

A

K sub a = ([H3O+][A-])/[HA]; the smaller Ka is the weaker the acid and the less it will dissociate; water is not included; weak acid Ka less than 1.0

26
Q

base dissociation constant of weak base (Kb)

A

K sub b = ([B+][OH-])/[BOH] from equation BOH (aq) ->

27
Q

conjugate acid

A

acid formed from a base gaining a proton

28
Q

conjugate base

A

base formed from an acid losing a proton

29
Q

products of strong acid + strong base reaction

A

salt and water; neutral when present in equimolar amounts in reactants

30
Q

product of reaction between strong acid and weak base

A

forms a salt but often no water because weak bases often are not hydroxides; cation of the salt is a weak acid and will react with water solvent reforming some of the weak base through hydrolysis; pH below 7

31
Q

products of weak acid and strong base

A

pH will be in basic range; salt hydrolyzes, with concurrent formation of hydroxide ions; more hydroxide than hydronium ions

32
Q

weak bases reacted with weak acids

A

pH of such a solution depends on relative strengths of the reactants: if Kb is greater than Ka it will be basic; and vice versa

33
Q

square root of an exponent

A

that exponent divided by 2.

34
Q

acid equivalent

A

equal to one mole of H+ (or more properly H3O+) ions

35
Q

base equivalent

A

equal to one mole of OH- ions

36
Q

polyvalent

A

acids or bases of which each mole liberates more than one acid or base equivalent (ex. H2SO4 (aq) + H2O (l) -> H3O+ + (HSO4)- and then (HSO4)- (aq) + H2O (l) ->

37
Q

normality

A

acidity or basicity of solution depends on concentration of acidic or basic equivalents that can be liberated; so each mole of H3PO4 yields three moles (equivalents) of H3O+. Therefore 2 M H3PO4 solution would be 6 N

38
Q

gram equivalent weight

A

the mass of a compound that produces one equivalent (one mole of charge) - if divalent then take the molecular weight of molecule and divide by 2 to get how many grams of that molecule it takes to produce one equivalent of H3O+ if it dissociates completely

39
Q

titration

A

a procedure used to determine the concentration of a known reactant in a solution; performed by adding small amounts of solution of known concentration (titrant) to a known volume of a solution of unknown concentration (titrand) until completion of reaction (equivalence point)

40
Q

equivalence point

A

in acid-base, reached when number of acid equivalents present in original solution equals the number of base equivalents added or vice-versa; strong acid/strong base will have this point at pH 7 but others won’t necessarily

41
Q

equation for unknown concentration of titrand

A

N sub a (V sub a) = N sub b (V sub b); Na and Nb = acid and base normalities; Va and Vb = volumes of acid and base solutions

42
Q

how to select ideal indicator

A

find pH of the reaction at equivalence point and then select indicator with pKa value closest to it; must be weaker acid or base than the acid or base being titrated

43
Q

endpoint

A

the point at which the indicator changes to its final color; should be a negligible difference from equivalence point that can be corrected for or ignored

44
Q

multiple equivalence on a graph

A

indicate that it is a polyvalent titration

45
Q

half-equivalence point

A

the center of the buffer region (point between two regions on polyvalent graph); occurs when half of a given species has been protonated or deprotonated

46
Q

buffer solution

A

consists of a mixture of weak acid and its salt (which is composed of its conjugate base and a cation) or a mixture of a weak base and its salt (which is composed of its conjugate acid and an anion); examples are acetic acid (CH3COOH) and its salt, sodium acetate (CH3COO-Na+); and ammonia (NH3) and its salt, ammonium chloride (NH4+Cl-)

47
Q

bicarbonate buffer system

A

conjugate pair in the plasma of blood: H2CO3/(HCO3)-; carbonic acid and bicarbonate; CO2 (g) + H20 (l) ->

48
Q

Henderson-Hasselbalch equation for weak acid buffer solution

A

pH = pKa + log [A-][HA]; [A-] = concentration of conjugate base and [HA] = concentration of weak acid; when conjugate base concentration = weak acid concentration pKa = pH because log (1) = 0; buffering capacity is optimal then

49
Q

Henderson-Hasselbalch equation for weak base buffer solution

A

pOH = pKb + log [B+]/[BOH]; [B+] = concentration of conjugate acid and [BOH] = concentration of weak base; when concentrations are equal pKb = pOH and buffering capacity is optimal

50
Q

buffering capacity

A

ability to which the system can resist changes in pH - if concentrations of acid and its conjugate base were doubled then capacity would double (meaning resistance to pH change would double) but not actual pH (which would not change); buffering capacity is usually maintained within 1 pH unit of the pKa value