Chapter 17: Acids and Bases

Question 1

carboxylic acid

Answer 1

An organic acid containing the functional group – COOH. It is often found in substances derived from living organisms. Acetic acid is an example.

Question 2

alkaloids

Answer 2

Organic bases found in plants that are often poisonous.

Question 3

Acid

Answer 3

A substance that produces H⁺ ions in aqueous solution.

Question 4

Base

Answer 4

A substance that produces OH^- ions in aqueous solution.

Question 5

Arrhenius definition

Answer 5

The definition of an acid as a substance that produces H⁺ions in aqueous solution ad a base as a substance that produces OH^- ions in aqueous solution.

Question 6

hydronium ion

Answer 6

H₃O⁺ ion, the ion formed from the association of a water molecule with an H⁺ ion donated by an acid.

Question 7

strong acid

Answer 7

Completely ionizes in solution. Represented by single arrow.

The concentration of H₃O⁺ in a strong acid solution is equal to the concentration of the strong acid because we ignore the contribution of the autoionization of water.

Question 8

weak acid

Answer 8

Partially ionizes. Represented with an equilibrium arrow (double).

The concentration of H₃O⁺ is not equal to the concentration of the weak acid. It is less acidic because it only partially ionizes. Needs to be solved by equilibrium technique.

Question 9

strong base

Answer 9

One that completely dissociates in solution.

Question 10

weak base

Answer 10

Partially ionizes in water.

Question 11

Bronsted-Lowry definition

Answer 11

The definitions of an acid as a proton (H⁺ ion) donor and a base as a proton acceptor.

Question 12

ampohteric

Answer 12

Substances that can act as acids or bases. i.e. water.

Question 13

conjugate acid-base pair

Answer 13

Two substances related to each other by the transfer of a proton.

i.e.: NH₄⁺ & NH₃

Question 14

Conjugate acid

Answer 14

Any base to which a proton has been added.

Question 15

conjugate base

Answer 15

Any acid from which a proton has been removed.

Question 16

monoprotic acids

Answer 16

Acids containing only one ionizable proton.

Hydrochloric acid (HCl)

Nitric acid(HNO3)

Hydrobromic acid (HBr)

Hydrioidic acid (HI)

Perchloric acid (HClO4)

Question 17

diprotic acid

Answer 17

An acid containing two ionizable protons.

Sulfuric acid (H₂SO₄)

Question 18

Triprotic

Answer 18

Acids containing three ionizable protons.

Phosphoric acid (H₃PO₄)

Question 19

Common Strong Acids

Answer 19

Hydrochloric acid (HCl)

Nitric acid(HNO3)

Hydrobromic acid (HBr)

Hydrioidic acid (HI)

Perchloric acid (HClO4)

Sulfuric acid (H₂SO₄)

Question 20

Common weak acids

Answer 20

Hydrofluoric acid (HF)

Acetic acid (HC₂H₃O₂)

Formic acid (HCHO₂)

Sulfurous acid (H₂SO₃)

Carbonic acid (H₂CO₃)

Phosphoric acid (H₃PO₄)

Question 21

Acid ionization constant (K_a)

Answer 21

Equilibrium constant for the ionization reaction of the weak acid. It is relatively small and the smaller the constant, the less the acid ionizes, and the weaker the acid.

K_a = [H₃O⁺][A^-]/[HA] = [H⁺][A^-]/[HA]

Question 22

Autoionization

Answer 22

The process when water acts as an acid and a base with itself.

H₂O(l) + H2O(l) ⇔ H₃O(aq) + OH^-(aq)

H2O(l) ⇔ H⁺(aq) + OH-(aq)

Question 23

ion product constant for water (K_w)

Answer 23

aka dissociation constant for water.

K_w = [H₃O⁺][OH^-] = [H⁺][OH^-]

At 25ºC, K_w=1.0 x 10^-14

In all aqueous solutions both H₃O⁺ and OH^- are present and K_w = 1E-14.

Question 24

acidic solution

Answer 24

An acid that creates additional H₃O⁺ ions, causing H₃O⁺ to increase.

[H₃O⁺] > [OH^-] BUT it still equals 1.0E-14 K_w

Question 25

basic solution

Answer 25

Contains a base that creates additional OH^- ions, causing it to increase and [H₃O⁺] to decrease but ion product constant still applies.

[OH^-] > [H₃O⁺]

Question 26

neutral

Answer 26

H₃O⁺ and OH^- are equal in concentrations.

Question 27

pH

Answer 27

A scale that is a compact way to specify the acidity of a solution. It is the negative of the log of the hydronium ion concentration.

pH = -log[H₃O⁺]

pH < 7 acidic

pH > 7 basic

pH = 7 neutral

Question 28

pOH

Answer 28

Analogous to the pH scale but with respect to [OH^-] instead.

pOH = -log[OH^-]

pOH < 7 basic

pOH > 7 acidic

pOH = 7 neutral

Question 29

pK_a

Answer 29

pK_a = -log K_a​

The pK_a of a weak acid is a way to quanitfy strength. The smaller the pK_a, the stronger the acid.

Question 30

percent ionization

Answer 30

The ratio of weak acid of the ionized acid concentration to the inital acid concentration, multiplied by 100%.

= [H₃O⁺]_equil/[HA]_initial X 100%

The percent ionization of a weak acid decreases with increasing concentration of the acid.

Question 31

Common strong bases

Answer 31

Lithium hydroxide (LiOH)

Sodium hydroxide (NaOH)

Potassium hydroxide (KOH)

Strontium hydroxide [Sr(OH)₂]

Calcium hydroxide [Ca(OH)₂]

Barium hydroxide [Ba(OH)₂]

Question 32

Common weak bases

Answer 32

Carbonate ion (CO₃^-)

Ammonia NH₃

Methylamine (CH₃NH₂)

Question 33

Base ionization constant

Answer 33

K_b, ionization of a weak base.

B = weak base

B(aq) + H₂O(l) ⇔ BH⁺(aq) + OH^-

K_b = [BH⁺][OH^-]/[B]

Smaller the K_b, the weaker the base. P scale can also be applied so that pK_b = -log K_b

Question 34

polyprotic acid

Answer 34

Ionizes in successive steps with its own K_a. Second ionization is smaller than the first and is true for all polyprotic acids because the first proton separates from a neutral molecule, while the second must separate from an anion. The negatively charged anion holds the positively charged proton more tightly, making the proton more difficult to remove and resulting in a smaller value of K_a.