STRUCTURAL EFFECTS ON ACIDITY

strength of an acid

The _ is determined by the stability of the conjugate base that forms when the acid loses its proton: the more stable the base, the stronger its conjugate acid.

base; conjugate acid

The strength of an acid is determined by the stability of the conjugate base that forms when the acid loses its proton: the more stable the _, the stronger its -.

base

The weaker the _, the stronger its conjugate acid or the more stable the base, the stronger its conjugate acid .

conjugate acid

The weaker the base, the stronger its _ or the more stable the base, the stronger its conjugate acid .

base

The weaker the base, the stronger its conjugate acid or the more stable the _, the stronger its conjugate acid .

conjugate acid

The weaker the base, the stronger its conjugate acid or the more stable the base, the stronger its _

HA (aq) ←→ H+ (aq) + A- (aq)

acid c. base

strong acid

high tendency to lose their proton; they’d rather done or lose their proton and exist without it. they want to lose proton (H+), it prepares to be in the conjugate base form. it exists without the proton; if it prefers to exist without the proton, it means A- is very small; it prefers to be left alone by the proton. high tendency to donate its proton and is very stable in cb form bcs it prefers to be without the proton.

High

The preference of a strong acid to exist without H⁺

Strong acid

The tendency of an acid to lose its proton easily

Conjugate base

The form an acid prefers after donating its proton

Proton (H⁺)

The particle lost by an acid during dissociation

A⁻

A stable form of a strong acid after losing H⁺

High

The strength of an acid when its conjugate base is weak

Stability

The reason why A⁻ does not accept back the proton

Complete

The extent to which HA dissociates in water

unstable

A conjugate base that prefers to reunite with a proton is _.

A-

After dissociation, strong acids mostly exist in the form of

donate

A strong acid has a high tendency to _ its proton.

A⁻

In strong acids, the conjugate base _ is more stable than HA.

HA

At equilibrium, weak acids mostly exist as _.

HA

In weak acids, _ is more stable than A-

stability

Weak acids mostly exist in the HA form because of _.

unionized (HA)

When the conjugate base is unstable, the acid prefers to stay in its _ form.

conjugate base

we usually determine the strength of an acid by determining the strength of its _

conjugate base (A-)

a strong acid (HA) has a weak

conjugate base

a weak acid has a strong_

STRONG ACID (HA)

Unstable

STRONG ACID (HA)

High tendency to lose proton

STRONG ACID (HA)

High tendency to accept electron pair

(negative charge)

WEAK CONJUGATE BASE (A-)

Stable

STRONG ACID (HA) OR WEAK CONJUGATE BASE (A-)?

WEAK CONJUGATE BASE (A-)

Low tendency to gain proton

STRONG ACID (HA) OR WEAK CONJUGATE BASE (A-)?

WEAK CONJUGATE BASE (A-)

Low tendency to donate electron pair

(negative charge)

STRONG ACID (HA) OR WEAK CONJUGATE BASE (A-)?

WEAK ACID (HA)

Stable

WEAK ACID (HA) OR STRONG CONJUGATE BASE (A-)

WEAK ACID (HA)

Low tendency to lose proton

WEAK ACID (HA) OR STRONG CONJUGATE BASE (A-)

WEAK ACID (HA)

Low tendency to accept electron pair

(negative charge)

WEAK ACID (HA) OR STRONG CONJUGATE BASE (A-)

STRONG CONJUGATE BASE (A-)

Unstable

WEAK ACID (HA) OR STRONG CONJUGATE BASE (A-)

STRONG CONJUGATE BASE (A-)

High tendency to gain proton

WEAK ACID (HA) OR STRONG CONJUGATE BASE (A-)

STRONG CONJUGATE BASE (A-)

High tendency to donate electron pair (negative charge)

WEAK ACID (HA) OR STRONG CONJUGATE BASE (A-)

Electronegativity

Hybridization

Size

Inductive Effect

Steric Effect

Pi Electron Delocalizaton/Resonance

Interaction of Structural Effects

STRUCTURAL EFFECTS ON

ACIDITY (7)

electronegative

The more _ an element is, the more it helps to stabilize the negative charge of the conjugate base.

conjugate base

The more electronegative an element is, the more it helps to stabilize the negative charge of the _.

strongest acid

When atoms are similar in size, the _ has its hydrogen attached to the most electronegative atom.

electronegative

hen atoms are similar in size, the strongest acid has its hydrogen attached to the most _ atom.

relative electronegativities

C < N < O < F

F

relative electronegativities

C < N < O < F

most electronegative

relative acidities

CH4 < NH3 < H2O < HF

HF

relative acidities

CH4 < NH3 < H2O < HF

strongest acid

relative stabilities

-CH3 < -NH2 < HO- < F-

F-

relative stabilities

-CH3 < -NH2 < HO- < F-

most stable

anion

_ is stabilized by having negative charge om a highly electronegative atom

HYBRIDIZATION

formation of hybrid orbitals from the combination of individual orbitals

HYBRIDIZATION

affects electronegativity.

HYBRIDIZATION

The most electronegative atom will be the one with its bonding electrons closest to the

nucleus.

nucleus

The most electronegative atom will be the one with its bonding electrons closest to the

_.

s

The strongest acid has its hydrogen attached to the atom with most _ character.

sp

sp > sp2 > sp3

most en

sp3

sp > sp2 > sp3

least en

sp

sp > sp2 > sp3

closer to nucleus

strongest acid (most en)

middle (acid)

weakest acid (not that en)

The size of the atom is more important than its electronegativity in determining acid strength.

size

acidity affects _ of cb

size

The _ of the atom is more important than its electronegativity in determining acid strength.

SIZE

As we go down a column in the periodic table, the atoms get larger, the electrons are more dispersed, and the stability of the atoms increases even though the electronegativity of the atoms decreases.

decreases

As we go down a column in the periodic table, the atoms get larger, the electrons are more dispersed, and the stability of the atoms increases even though the electronegativity of the atoms _.

hydrogen

The strongest acid has its _ attached to the largest atom.

I-

F- < Cl- < Br- < I-

largest

HI

HF < HCl < HBr < HI

strongest acid

60

CH4 pKa

36

NH3 pKa

15.7

H2O pKa

7.0

H2S pKa

3.2

HF pKa

-7

HCl pKa

-9

HBr pKa

-10

HI pKa

50%

sp %

33%

sp2 %

25%

sp3 %

electronegativity

when u belong to the same period, what matters is the _ than the size (sizes r somewhat similar)

HC≡C- + CH3CH3 (more favorable)

H2C=CH- + HC≡CH (backward rxn more favorable)

CH3CH2- + H2C=CH2 (backward rxn more favorable)

WEAKER

RXN IS MORE FAVORABLE WHEN THE STRONGER ACID PROTONATES THE _ ONE

oxygen

Which is more electronegative, oxygen or sulfur?

H2S

Which is a stronger acid, H2O or H2S?

CH3SH

Which is a stronger acid, CH3OH or CH3SH?

HBr (size is bigger, more stable)

Which is a stronger acid?

HCl or HBr

CH3CH2CH2O+H2

Which is a stronger acid?

oxygen

Which is a stronger acid?

Which is a stronger acid?

size

same grp diff period