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Chm 2 > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

acids

A

Donate H+

Molecules - Both organic and inorganic
Cations that contain H
Anions that contain H

Binary acids have acid hydrogens attached to a nonmetal atom.
ex HCl, HF

Oxyacids have acid hydrogens attached to an oxygen atom.
ex H2SO4, HNO3

Carboxylic acids have COOH group. only 1st H in the formula is acidic
ex HC2H3O2, H3C6H5O7

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2
Q

bases

A

accept H+, usually contain OH-

Ionic compounds that contain OH-
Molecules - Primarily amines
Anions – With and without H
Cations – Few examples

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3
Q

Definitions of Acids and Bases:

A

Arrhenius, Bronsted-Lowry, Lewis

Brønsted–Lowry definition: Based on reactions in which H+ is transferred

Lewis definition

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4
Q

Arrhenius Theory

A

Based on H+ and OH-

Acids: produce H+ ions in aqueous solution.
ex HCl(aq) → H+(aq) + Cl−(aq)

Bases: produce OH− ions in aqueous solution.
ex NaOH(aq) → Na+(aq) + OH(aq)

The H+ from the acid combines with the OH− from the base to make a molecule of H2O.
It is often helpful to think of H2O as H—OH.

The cation from the base combines with the anion from the acid to make a salt.
acid + base → salt + water
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

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5
Q

Problems with Arrhenius Theory

A

It does not explain why molecular substances, such as NH3, dissolve in water to form basic solutions, even though they do not contain OH– ions.

It does not explain how some ionic compounds, such as Na2CO3 or Na2O, dissolve in water to form basic solutions, even though they do not contain OH– ions.

It does not explain why molecular substances, such as CO2, dissolve in water to form acidic solutions, even though they do not contain H+ ions.

It does not explain acid–base reactions that take place outside aqueous solution.

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6
Q

Hydronium ion

A

H3O+

The H+ ions produced by the acid are so reactive they cannot exist in water.
H+ ions are protons!

Instead, they react with water molecules to produce complex ions, mainly hydronium ion, H3O+.
H+ + H2O  H3O+

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7
Q

Bronsted/Lowry Definition of acid and base

A

Brønsted-Lowry Acid – A compound that donates a proton to another compound. H+

Brønsted-Lowry Base – A compound that accepts a proton from another compound.

It defines acids and bases based on what happens in a reaction.
Any reaction involving H+ (proton) that transfers from one molecule to another is an acid–base reaction, regardless of whether it occurs in aqueous solution or if there is OH− present.

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8
Q

binary acid

A

acid hydrogens attached to nonmetal atom

HCl, HBr, HI, HF

HF is weak acid, others strong

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9
Q

ocyacids

A

acid hydrogens attached to an oxygen atom

H2SO4, HNO3

higher the #oxygens (oxidation number) the stronger the acid
H2SO4 > H2SO3; HNO3 > HNO2

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10
Q

Carboxylic acids

A

have a COOH group

Only the 1st acid in the formula is acidic

ex HC2H3O2, H3C6H5O7

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11
Q

STRONG Acids

A

Ka>1;
[H30+]>[OH-]
dissociates (ionizes) completely
donate practically all their H’s.
100% ionized in water
a strong electrolyte

[H3O+] = [strong acid]
yield nearly 100% H30+

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12
Q

Common Strong Acids

A

HCl, HBr, HI, HNO3, H2SO4, HClO4

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13
Q

WEAK Acids

A

Ka<1;
dissociates (ionizes) partially; only a small percentage of the molecules ionize;much less than 1% ionized in water
weak electrolyte

[H3O+] &laquo_space;[weak acid]
yield much less than 100% H30+

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14
Q

STRONG Bases

A

Kb>1;
[OH-]>[H30+]
dissociates (ionizes) completely in H20; Practically all the base molecules form OH– ions
a strong electrolyte

[OH-] = [strong base]

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15
Q

Common Strong Bases

A

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

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16
Q

weak bases

A

Kb<1;
dissociates (ionizes) partially
weak electrolyte
only a small percentage of the base molecules form OH- ions, either through dissociation or reaction with water

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17
Q

Conjugate pairs

A

An acid donates a proton and becomes a conjugate base.

A base accepts a proton and becomes a conjugate acid.

Each reactant and the product it becomes is called a conjugate pair.

In a Brønsted-–Lowry acid–base reaction, the original base becomes an acid in the reverse reaction. the original acid becomes a base in the reverse process.

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18
Q

Bronsted-Lowry Acid

A

H+ donors.
Any material that has H can potentially be a Brønsted–Lowry acid.
Because of the molecular structure, often one H in the molecule is easier to transfer than others.

When HCl dissolves in water, the HCl is the acid because HCl transfers an H+ to H2O, forming H3O+ ions.
Water acts as base, accepting H+.

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19
Q

Bronsted-Lowry Base

A

H+ acceptors.
Any material that has atoms with lone pairs can potentially be a Brønsted–Lowry base.
Because of the molecular structure, often one atom in the molecule is more willing to accept H+ transfer than others.

When NH3 dissolves in water, the NH3(aq) is the base because NH3 accepts an H+ from H2O, forming OH–(aq).
Water acts as acid, donating H+.

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20
Q

amphoteric substance

A

can act as either an acid or a base because they have both transferable H and an atom with lone pair electrons.

ex H20

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21
Q

Kw

A

ion product of water
product of [H3O+] and [OH-]

Kw= 1.00x10^-14 at 25*C

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22
Q

[H3O+] and [OH-]

A

[H3O+] and [OH-] are equal in pure water

[H3O+] and [OH-] are inversely related to each other

[H3O+] >1.00x10^-7 ACIDIC
[OH-]>1.00x10^-7 BASIC
[H3O+] = [OH-] NEUTRAL

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23
Q

pH

A

pH = -log[H3O+]
and [H3O+] = 10^-pH

pHwater = -log[10^-7] = 7
pH < 7 ACIDIC
pH > 7 BASIC
pH = 7 NEUTRAL

24
Q

pOH

A

pOH = -log[OH-]
and [OH-] = 10^-pOH

pOHwater = -log[10^-7] = 7
pOH < 7 BASIC
pOH > 7 ACIDIC
pOH = 7 NEUTRAL

25
Q

pH + pOH =

A

14

26
Q

relative ion concentration and pH

A

pH < 7; ACIDIC;
[H3O+] > [OH-]

pH > 7; BASIC;
[H3O+] < [OH-]

pH = 7; Neutral;
[H3O+] = [OH-]

27
Q

The farther the equilibrium position lies toward the products, the ____.

A

stronger the acid or base.

Commonly, acid or base strength is measured by determining the equilibrium constant of a substance’s reaction with water.
HAcid + H2O ⇌ Acid− + H3O+
Base: + H2O ⇌ HBase+ + OH−

28
Q

The stronger an acid is at donating H,

A

the weaker the conjugate base is at accepting H.

29
Q

Higher oxidation number =

A

stronger oxyacid
H2SO4 > H2SO3; HNO3 > HNO2

30
Q

Cation stronger acid than

A

neutral molecule; neutral stronger acid than anion
H3O+ > H2O > OH−; NH4+ > NH3 > NH2−

Trend in base strength opposite

31
Q

pH

A

= -log [H3O+]

32
Q

pOH

A

= -log [OH-]

33
Q

pH + pOH

A

14

34
Q

Ka (acid ionization constant)

A

Ka = [H3O+][A-]/[HA]

Ka = 10^-pKa

Ka and Kb are inversely related

35
Q

pKa

A

a way of expressing the strength of an acid or base

pKa = -log(Ka)

the stronger the acid the smaller the pKa (larger Ka)

36
Q

Kb (base ionization constant)

A

Kb = [OH-][H:B]/[B]

Kb = 10^-pKb

Ka and Kb are inversely related

37
Q

pKb

A

a way of expressing the strength of an acid or base

pKb = -log(Kb)

the stronger the base the smaller the pKb (larger Kb)

38
Q

Salts

A

ionic compounds (metal and nonmetal)

can be soluble or insoluble in water

soluble salts act as acid, base, or neutral in water

Salts that consist of
1. anions that are the conjugate base of STRONG acids are NEUTRAL in water (pH=7; ex: HCl, KOH, NaNO3)

  1. anions that are conjugate bases of WEAK acids are BASIC in water (pH>7; ex NaCN, CH3CO2Na, KF)
  2. cations that are the conjugate acids of WEAK bases are ACIDIC in water (pH<7; ex NH4Cl +H20 -> acidic and H20 is the weak base)
39
Q

Salts: cations of group I and II metals are always ___

A

neutral

transition metals have acidic properties

40
Q

Buffer

A

resist changes in pH

weak acid and its conjugate base or weak base and its conjugate acid

41
Q

buffer capacity

A

amount of acid or base a buffer can neutralize

depends on 1. the relative amounts of acid and base, and 2. the absolute concentrations of acid and base

most effective when acid and base are equal concentrations
[base]:[acid]=1

will be effective when
0.1< [base]:[acid] < 10

42
Q

Henderson-Hasselbalch equation

A

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

pOH = pKb + log ([salt]/[base])

43
Q

titration curve

A

plot of pH versus the amount of added titrant

midpoint of the vertical part of the curve is the equivalence point

44
Q

acid ionization

A

reaction involving the transfer of a proton from an acid to water, yielding hydronium ions and the conjugate base of the acid

45
Q

autoionization

A

reaction between identical species yielding ionic products; for water, this reaction involves transfer of protons to yield hydronium and hydroxide ions

46
Q

base ionizations

A

reaction involving the transfer of a proton from water to a base, yielding hydroxide ions and the conjugate acid of the base

47
Q

diprotic acid

A

acid containing two ionizable hydrogen atoms per molecule

48
Q

diuretic base

A

base capable of accepting two protons

49
Q

ion-product constant for water (Kw)

A

equilibrium constant for the auto ionization of water

50
Q

percent ionization

A

ratio of the concentration of ionized acid to initial acid concentrations expressed as a percentage

51
Q

common ion effect

A

effect on equilibrium when a substance with an ion in common with the dissolved species is added to the solution; causes a decrease in the solubility of an ionic species, or a decrease in the ionization of a weak acid or base (le chattliers)

52
Q

dissociation constant (Kd)

A

equilibrium constant for the decomposition of a complex ion into its components

53
Q

formation constant (Kf)

A

also stability constant

equilibrium constant for the formation of a complex ion from its components

54
Q

lewis acid
lewis base

A

Lewis acid: accepts a pair of elections

Lewis base: donates a pair of electrons

55
Q

coordinate covalent bond (dative bond)

A

a type of bond that forms when one of the atoms in the bond provides both bonding electrons

56
Q

lewis acid base adduct

A

a compound that contains a coordinate covalent bond formed between a lewis acid and lewis base

Chm 2 (3 decks)

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