Acid Base Equilibria and Titrations

Question 1

What are the strong acids

Answer 1

HI
HBr
HCl
HClO₃
HClO₄
H₂SO₄
HNO₃
(So I Brought No Clean Clothes)

Question 2

What are the strong bases

Answer 2

Group 1 metal hydroxides
Mg(OH)₂
Ca(OH)₂
Sr(OH)₂
Ba(OH)₂

Question 3

Creating an acidic buffer

Answer 3

Mixing a weak acid and its conjugate base in a 1:1 ratio

Question 4

Creating an alkaline buffer

Answer 4

Mixing a weak base and its conjugate acid in a 1:1 ratio

Question 5

Lewis acid

Answer 5

Species that can accept an electron pair

Question 6

Lewis base

Answer 6

Species that can donate can electron pair

must contain a lone pair of electrons

Question 7

What are some common Lewis acids?

Answer 7

Metal cations: K⁺, Mg²⁺, Ca²⁺, Fe³⁺
Neutral compounds of boron, aluminum
Other group 13 elements: BF₃, AlCl₃
Protons (H⁺)

Question 8

What makes a good Lewis acid?

Answer 8

When the central atom can most readily accept an electron pair

Question 9

Acid/base and conjugate acid/base relationship:

Answer 9

The stronger the acid = the weaker the conjugate base
The weaker the acid = the stronger the conjugate base
The stronger the base = the weaker the conjugate acid
The weaker the base = the stronger the conjugate acid

Question 10

As pKa/pKb goes down, Ka/kb _______ and acid/base strength ________
As pka/pkb goes up, Ka/kb __________ and acid/base strength _________

Answer 10

Increases, increases
Decreases, decreases

Question 11

Metal oxides produce ________ solutions in water

Answer 11

Basic

Question 12

Non-metal oxides produce ________ solutions in water

Answer 12

Acidic

Question 13

General trend for acidity for oxyacids

Answer 13

• The more oxygen atoms, the more acidic because there are more oxygens for the electrons to spread out onto in the conjugate base
• for oxyacids with the same number of oxygen atoms, acid strength increases with electronegativity: HClO₄ > HBrO₄ > HIO₄

Question 14

the ______ is placed in an Erlenmeyer flask during a titration

Answer 14

analyte

Question 15

the _______ is placed in a burrette during a titration

Answer 15

titrant

Question 16

what is the equivalence point in an acid-base titration?

Answer 16

the point at which the moles of H+ ions in solution is equal to the moles of OH- ions
usually the steepest part of the titration curve

Question 17

what titrations involve a half-equivalence point?

Answer 17

titrations involving weak acid/strong base or a weak base/strong acid

Question 18

what is the half-equivalence point in a titration curve?

Answer 18

the midpoint of the buffering region, the part of the curve where the pH of the solution is not drastically affected

Question 19

what is the process of an acid-base titration?

Answer 19

the concentration of an analyte is determined by gradually adding small volumes of a solution with a known concentration (the titrant). titrant is added until the reaction completes at a certain equivalence point, which can be viewed by color changes or on a graph

Question 20

at the equivalence point, what formula can be used to determine the concentration of the analyte?

Answer 20

N_aV_a = N_bV_b (using normality) or M_aV_a = M_bV_b (molarity)

Question 21

strong acid + strong base = equivalence point at pH

Answer 21

= 7

Question 22

strong acid + weak base = equivalence point at pH

Answer 22

< 7

Question 23

weak acid + strong base = equivalence point at pH

Answer 23

> 7

Question 24

all monoprotic strong acid and strong base titrations will have an equivalence point at pH ______

Answer 24

7

Question 25

arrhenius acid

Answer 25

any species that dissolves in aqueous solution to produce H+ ions | arrhenius acids are bronsted-lawry acids --> both release protons

Question 26

arrhenius base

Answer 26

any species that dissolves in aqueous solution to produce OH- ions

Question 27

formula for calculating pH:

Answer 27

pH = -log[H⁺]

Question 28

formula for calculating pOH:

Answer 28

pOH = -log[OH^-]

Question 29

what is the pH of water?

Answer 29

* 7 * it contains the same number of hydrogen ions and hydroxide ions * [H⁺][OH^-] = (1 x 10^-7 M)

Question 30

what is the constant k_w of water?

Answer 30

* water dissociates to produce H⁺ and OH^- * the constant k_w = [H⁺][OH^-] = (1 x 10^-7 M)² = 1 x 10^-14

Question 31

strength of binary acids:

Answer 31

* binary acids: HCl, HBr, HI * HCl > HBr > HI * HI is the strongest because it has the largest atomic radius which causes the bond length to become longer and the bond strength to be **weaker**

Question 32

neutralization reaction:

Answer 32

* when a strong acid reacts with a strong base to form salt and water * all protons (H⁺) and hydroxide ions (OH^-) present in the solution combine to form water and the reaction goes to completion * the salt produced is **neutral**

Question 33

reaction that form salts may occur between:

Answer 33

* strong acid and a strong base * strong acid and a weak base * weak acid and a strong base

Question 34

reaction between a strong acid and a weak base:

Answer 34

* results in an acidic salt * the conj. base of the strong acid is considered to be neutral * the conj. acid of the weak base is considered to be acidic * ex: HCl + NH₃ -> NH₄Cl

Question 35

reaction between a weak acid and a strong base:

Answer 35

* results in a basic salt * the conjugate base of the weak acid is basic * the conjugate base of the strong base is neutral

Question 36

what formula is used to calculate the pH of a buffer solution?

Answer 36

* Henderson-Hasselbalch equation: * pH = pK_a + log([A^-]/[HA]) * [A^-] = concentration of conj. base * [HA] = concentration of weak acid