CH 320M: Chem Activity 5C - Acid Base Reactions and pKa

The smaller the pKa, the _ the acid

stronger

The larger the pKa, the _ the acid

weaker

Acids are defined as strong if

it is easy to rip away their hydrogens

Bases are defined as strong if

they easily take up more hydrogens

When creating arrows, -pKa is

the energy released when a bond forms

When creating arrows, +pKa is

the energy needed to break a bond

To break a bond between Fluorine and Hydrogen it takes

+3 pKa

To form a bond between Fluorine and Hydrogen it releases

-3 pKa

To break a bond between a Nitrogen with 4 R groups it takes

+9 pKa

To form a bond between a Nitrogen with 3 R groups it releases

-9 pKa

To break a bond between an Oxygen with 2 R group it takes

+16 pKa

To form a bond between an Oxygen with 1 R group it releases

-16 pKa

To break a bond between a Nitrogen with 3 R groups it takes

+35 pKa

To form a bond between a Nitrogen with 2 R groups it releases

-35 pKa

To break a bond between two Hydrogens it takes

+40 pKa

To break a bond between two Hydrogens it needs

+40 pKa

To break a bond between Carbon and a Hydrogen it takes

+50 pKa

To form a bond between Carbon and a Hydrogen it releases

-50 pKa

Strong acids have a pKa of _ when breaking bonds

+0 pKa

Strong acids have a pKa of _ when forming bonds

-0 pKa

Strong acids have a pKa equivalent to +0 when breaking bonds because

it is extremely easy to take away Hydrogens from it

Formal charge trumps

electronegativity

Formal charge effect states that an H on a +1 atom is (usually)

more acidic than an H on a neutral atom

The formal charge effect also states that an H on a neutral atom is (usually)

more acidic than an H on a -1 atom

If a hydrogen is more acidic, that means

it is the H that takes the least amount of energy to pull

For a given base, the larger the pKa of the conjugate acid, the _ the base

stronger

For a given base, the smaller the pKa of the conjugate acid the _ the base

weaker

What is the pKa of acetic acid?

5

What is the pKa of C2H2

25

What is the pKa of C6H6O

10