Lecture 7: Acids And Bases

Question 1

Arrhenius acids/bases

Answer 1

1. Acid: anything that supplies a hydrogen ion in aqueous solution
2. Base: anything that supplies hydroxide ion in aqueous solution

Question 2

Bronsted acid/base

Answer 2

1. Acid: anything that donates a proton
2. Base: anything that accepts a proton

Question 3

Lewis acid/base

Answer 3

1. Acid: anything that accepts a pair of electrons
2. Base: anything that donates a pair of electrons
3. This pair shares a coordinate covalent bond (1 atom (base) donates both electrons)

Question 4

PH

Answer 4

1. PH=-log[H+]
2. Acidic <7<basic
   2a. At each point on pH scale, there is a tenfold difference in [H+]

Question 5

KW

Answer 5

1. autoionization of water: water donates and accepts proton in the same reaction
2. Equations
   2a. Kw=[OH-][H+]
   2b. PKw=pH+pOH
3. At 25C:
   3a. Kw=10^-14, pKw=14, 14=pH+pOH
   3b. PH=-log[H+]
   3c. POH=-log[OH-]

Question 6

Ka and K

Answer 6

1. HA+ H2O —> H3O+ +A-
   1a. Ka=[H+][A-]/[HA]
2. A- + H2O —->OH- + HA
   2a. Kb=[OH-][HA]/[A-]
3. PKa+pKb=pK=14

Question 7

Strong acids

Answer 7

1. The stronger the acid=the weaker its conjugate
   1a. Strong acid completely dissociates in water
2. HI, HBr, HCL, HNO3, HCLO4

Question 8

Periodic trends of acidity

Answer 8

1. Low polarity=low bond strength=high acidity

Question 9

Salts

Answer 9

1. Ionic compounds that dissociate in water

Question 10

Titrations

Answer 10

1. Equivalence point (vertical): ph=pi
2. Midpoint (horizontal): ph=pka

Question 11

Henderson hasselbalch equation

Answer 11

1. PH=pKa + log ([A-]/[HA])