Chapter 16 - Acid-Base Equilibria

Question 1

Properties of acidic solutions are due to what?

Answer 1

H+(aq) ions

Question 2

Properties of basic solutions are due to what?

Answer 2

OH-(aq) ions

Question 3

What is an H+ ion?

Answer 3

It is simply a proton with no surrounding valence electrons.

Question 4

What is a hydronium ion and what is it used for?

Answer 4

H3O+(aq) and it is often used to represent the

predominant form of H+ in water instead of the simpler H+(aq).

Question 5

What is a Bronsted-Lowry acid?

Answer 5

A substance that donates a proton to another substance.

Question 6

What is a Bronsted-Lowry base?

Answer 6

A substance that accepts a proton from another substance.

Question 7

When is a substance amphiprotic?

Answer 7

When it can act as either a Bronsted-Lowry base or acid

Question 8

What is the conjugate acid of the base?

Answer 8

When a proton is added to the base.

Question 9

What is the conjugate base of the acid?

Answer 9

When a proton is removed from the acid.

Question 10

What is a conjugate acid-base pair?

Answer 10

When an acid and its conjugate base (or a base and its conjugate acid) are combined.

Question 11

What is autoionization of water?

Answer 11

Two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton.
(H₂O + H₂O ⇌ H₃O⁺ + OH⁻)

Question 12

What is the ion-product constant for water?

Answer 12

Kw=[H+][OH-]=1.0x10^-14 at 25°C.

Question 13

What is pH (it’s a formula)?

Answer 13

pH=-log[H+]

Question 14

At 25°C, what are the pH levels of neutral, acidic, and basic solutions, respectively?

Answer 14

Neutral pH=7.00
Acidic pH=less than 7
Basic pH=more than 7

Question 15

What’s pOH (it’s a formula)?

Answer 15

pOH=-log[OH-]

Question 16

How is the relationship between pH and pOH calculated?

Answer 16

pH+pOH=14.00

Question 17

What are strong acids?

Answer 17

They are strong electrolytes that ionize completely in aqueous solution.

Question 18

What are the 7 most common strong acids?

Answer 18

1. HCl
2. HBr
3. HI
4. HNO3
5. HClO3
6. HClO4
7. H2SO4

Question 19

What are two common strong bases?

Answer 19

1. Ionic hydroxides of the alkali metals

2. Heavy alkaline earth metals

Question 20

What are weak acids?

Answer 20

A weak acid (AKA weak electrolyte) is an acid that is partially dissociated in an aqueous solution.

Question 21

What is the acid-dissociation constant (Ka) equal to?

Answer 21

It’s equal to the equilibrium constant ([Products]/[Reactants]).

Question 22

The larger the value of Ka, ___?

Answer 22

The stronger the acid.

Question 23

What are polyprotic acids?

Answer 23

Acids that have more than one ionizable proton (ex: H3PO4).

Question 24

Why do the acid-dissociation constants of polyprotic acids decrease in the order Ka1>Ka2>Ka3?

Answer 24

Because nearly all the H+ in a polyprotic acid comes from the first dissociation step (meaning not much H+ is left after the first step).

Question 25

How is the relationship between Ka and Kb expressed and what does it mean?

Answer 25

Ka*Kb=Kw.

The acid-dissociation constant of an acid and the base-dissociation constant of its conjugate base equals Kw.

Question 26

What is hydrolysis?

Answer 26

Hydrolysis is a chemical reaction in which H2O is split into H+ and OH- and combines with and combines with the cations and anions of a chemical compound.

Question 27

What are oxyacids?

Answer 27

Acids in which OH groups are bound to a central atom.

Question 28

What is a Lewis acid?

Answer 28

An electron-pair acceptor.

Question 29

What is a Lewis base?

Answer 29

An electron-pair donator.

Question 30

What are carboxylic acids?

Answer 30

Organic acids containing the COOH group.