Ch. 10: Acids and Bases

Question 1

Arrhenius Acids

Answer 1

Dissociate to produce an excess of hydrogen ions in soln

Question 2

Arrhenius Bases

Answer 2

Dissociate to produce and excess of hydroxide ions in solution

Question 3

Bronsted-Lowry Acids

Answer 3

Species that can donate hydrogen ions

Question 4

Bronsted-Lowry Bases

Answer 4

Species that can accept hydrogen ions

Question 5

Lewis Acids

Answer 5

Electron-pair acceptors

Question 6

Lewis Bases

Answer 6

Electron-pair donors

Question 7

Statements

Answer 7

All Arrhenius acids and bases are Bronsted-Lowry acids and bases, and all bronsted-lowry acids and bases are lewis acids ands and bases; however, the converse of these statements is not necesarily true

Question 8

Amphoteric

Answer 8

Species which can behave as acids or bases

Question 9

Amphiprotic

Answer 9

Species which can specifically behave as Bronsted lowry acids or bases

Question 10

Water

Answer 10

Classic example of an amphoteric, amphiprotic species– it can accept a hydrogen ion to become a hydronium ion, or it can donate a hydrogen ion to become a hydroxide ion

Question 11

Conjugate Species of Polyvalent acids and bases

Answer 11

Can also behave as amphoteric and amphiprotic species

Question 12

Water Dissociation constant Kw

Answer 12

10^-14 at 298K. Like other equilibrium constants, Kw is only affected by changes in temp

Question 13

pH and pOH

Answer 13

Can be calculated given the concentrations of H3O+ and OH- ions, respectively. In aqueous solns, pH+pOH=14 at 298K

Question 14

Strong acids and bases

Answer 14

Completely dissociate in solution

Question 15

Weak acids and bases

Answer 15

Do not completely dissociate in solution and have corresponding dissociation complexes (Ka and Kb)

Question 16

Conjugate Acids and Bases

Answer 16

In the Bronsted-Lowry def, acids have conjugate bases that are formed when the acid is deprotonated. Bases have conjugate acids that are formed when the base is protonated

• Strong acids and bases have very weak (inert) conjugates
• Weak acids and bases have weak conjugates

Question 17

Neutralization reactions

Answer 17

From salts and (sometimes) water

Question 18

Equivalent

Answer 18

Defined as one mole of the species of interest

Question 19

Normality

Answer 19

In acid-base chemistry, normality is the concentration of acid or base equivalents in solution

Question 20

Polyvalent

Answer 20

Acids and bases that can donate or accept multiple electrons. The normality of a solution containing a polyvalent species is the molarity of the acid or base times the number of protons it can donate or accept.

Question 21

Titrations

Answer 21

Used to determine the concentration of a known reactant in a soln

Question 22

Titrant

Answer 22

Has a known concentration and is added slowly to the titrand to reach the equivalence point

Question 23

Titrand

Answer 23

Has an unknown concentration but a known volume

Question 24

Half-equivalence point

Answer 24

Midpoint of the buffering region, in which half of the titrant has been protonated (or deprotonated); thus, [HA] = [A-] and a buffer is formed

Question 25

Equivalence Point

Answer 25

Indicated by the steepest slope in a titration curve; it is reached when the number of acid eqivalents in the original soln equals the number of base equivalents added or vice versa

Question 26

pH values of acids and bases

Answer 26

- Strong acid and strong base titrations have equivalence points at pH = 7 - Weak acid and strong base titrations have equivalencce points at pH > 7 - Weak base and strong acid titrations have equivalencce points at pH < 7 - Weak acid and weak base titrations can have equivalence points above or below 7 depending on the relative strength of the acid and base

Question 27

Indicator

Answer 27

Chosen for a titration, should have a pKa close to the pH of the expected equivalence point

Question 28

Endpoint

Answer 28

When the indicator reaches its final color in a titration

Question 29

Polyvalent acid/base titrations

Answer 29

Multiple buffering regions and equivalence points are observed

Question 30

Buffer solutions

Answer 30

Consist of a mixture of a weak acid and its conjugate salt or a weak base its conjugate salt; they resist large fluctuations in pH

Question 31

Buffering capacity

Answer 31

Refers to the ability of a buffer to resist changes in pH; Maximal buffering capacity is seen within 1 pH point of the pKa of the acid in the buffer soln

Question 32

Henderson-Hasselbalch Equation

Answer 32

Quantifies the relationship between pH and pKa for weak acids and between pOh and pKb for weak bases; when a soln is optimally buffered, pH = pKa and pOH = pKb