Chapter 4

Question 1

Arrhenius Acid

Answer 1

substances that produce H3O+ ions in aqueous solution

Question 2

Arrhenius bases

Answer 2

a substance that produces OH- in aqueous solutions

Question 3

Bronsted-Lowry Acid

Answer 3

proton donor

Question 4

Bronsted-Lowry Base

Answer 4

proton acceptor

Question 5

strength of acid/base

Answer 5

determined by how much of each component is present in a reaction; expressed by an equilibrium constant (Keq)
-logKa = pKa

Question 6

pKa

Answer 6

=-logKa
more negative the pKa, the stronger the acid
least negative pKa = strong base

Question 7

Acid/Base Equilibrium

Answer 7

• equilibrium favors reaction of the stronger acid and stronger base to give weaker acid and weaker base
• equilibrium constant (Keq) is used to tell us if an acid/base reaction favors product formation (Keq>1) or not (Keq<1), or if both reactant and product are equal (Keq=1)

Question 8

how to calculate Keq

Answer 8

1. determine pKa values for the acid reactant and conjugate acid product
2. take the difference in pKa (reactant-product)
3. take the antilog of -pKeq (Keq=10^-pKeq)

Question 9

reaction mechanism

Answer 9

a step-by-step description of how a chemical reaction occurs (narrow pushing)
-for acid/base reactions this deals with the transfer of a proton from an acid to a base

Question 10

thermochemistry

Answer 10

study of the energy of chemical structures
-in reality, these acid/base reactions occur when they come into contact with one another, which then leads to a transition state, or an activated complex that is the highest energy point during the reaction

Question 11

reaction coordinate diagrams

Answer 11

used to graphically represent changes in energy during a chemical reaction (energy vs reactions)

Question 12

structure to acidity relationship

Answer 12

• the key point to consider when determining relative acidities for neutral organic acids is the stability of the conjugate base anion (A-) that comes from the loss of a proton
• the more stable the anion (A-) the greater the acidity of the acid HA

Question 13

ways to stabilize A-

Answer 13

1. electronegativity (negative charge on more EN atom)
2. polarizability (negative charge on larger atom, spreading out e-)
3. resonance (delocalization of the negative charge)
4. inductive effect (spreading the negative charge onto an EWG)
5. hybridization (negative charge in orbital w/ more s character)

Question 14

lewis acid

Answer 14

molecule or ion that can form a new covalent bond by accepting a pair of electrons

Question 15

Lewis base

Answer 15

molecule or ion that can form a new covalent bond by donating a pair of electrons

Question 16

electron density

Answer 16

high electron density regions on molecules or ion react with low electron density regions of other molecules or ions, resulting a new covalent bond

Question 17

nucleophiles

Answer 17

e- rich species love nuclei

Question 18

electrophiles

Answer 18

e- poor species (electron loving)