Unit 8 Short Answer

Question 1

Autoionization of Water

Answer 1

Kw=[ H3O

Question 2

What is the autoionization of water?

Answer 2

The autoionization of water is the process by which water molecules dissociate into hydronium (H3O+) and hydroxide (OH-) ions.

Question 3

True or False: The equilibrium constant for the autoionization of water is known as Kw.

Answer 3

True

Question 4

Fill in the blank: The value of Kw at 25°C is __________.

Answer 4

1.0 x 10^-14

Question 5

What are the two ions produced during the autoionization of water?

Answer 5

Hydronium (H3O+) and hydroxide (OH-) ions.

Question 6

If [H3O+] = 1.0 x 10^-7 M, what is the concentration of [OH-] at 25°C?

Answer 6

[OH-] = 1.0 x 10^-7 M

Question 8

What is the pH of a 0.1 M strong acid solution?

Answer 8

The pH is 1.

Question 9

True or False: The pH of a strong base solution is calculated the same way as a strong acid solution.

Answer 9

True.

Question 10

Fill in the blank: The formula to calculate pH is __________.

Answer 10

-log[H+]

Question 11

What is the pH of a 0.01 M NaOH solution?

Answer 11

The pH is 12.

Question 12

What type of acid is acetic acid?

Answer 12

Weak acid.

Question 13

What is the pH of a 0.1 M weak acid solution if the acid dissociation constant (Ka) is 1.8 x 10^-5?

Answer 13

Approximately 2.87.

Question 14

Multiple Choice: Which of the following is a strong base? A) NaCl B) HCl C) NaOH D) CH3COOH

Answer 14

C) NaOH.

Question 15

What does a pH of 7 indicate?

Answer 15

Neutral solution.

Question 16

True or False: Strong acids completely dissociate in water.

Answer 16

True.

Question 17

How do you calculate the concentration of H+ ions in a strong acid solution?

Answer 17

It is equal to the molarity of the acid.

Question 18

What is the pH of a solution with a hydrogen ion concentration of 1 x 10^-6 M?

Answer 18

The pH is 6.

Question 19

Fill in the blank: A pH less than 7 indicates a __________ solution.

Answer 19

Acidic.

Question 20

Multiple Choice: Which of the following will have a higher pH? A) 0.1 M HCl B) 0.1 M NaOH

Answer 20

B) 0.1 M NaOH.

Question 21

What is the relationship between pH and pOH?

Answer 21

pH + pOH = 14.

Question 22

How does temperature affect pH?

Answer 22

pH can change with temperature due to changes in ion concentration.

Question 24

What is pH a measure of?

Answer 24

pH is a measure of the hydrogen ion concentration in a solution.

Question 25

What is the pH range for acidic solutions?

Answer 25

The pH range for acidic solutions is 0 to 6.9.

Question 26

What is the pH range for basic solutions?

Answer 26

The pH range for basic solutions is 7.1 to 14.

Question 27

What is considered a neutral pH?

Answer 27

A neutral pH is 7.

Question 28

True or False: Weak bases completely dissociate in water.

Answer 28

False.

Question 29

How do you calculate the pH of a strong acid?

Answer 29

For a strong acid, pH = -log[H+], where [H+] is the concentration of the acid.

Question 30

Fill in the blank: The formula for calculating pOH is ___

Answer 30

pOH = -log[OH-].

Question 31

What is the relationship between pH and pOH?

Answer 31

pH + pOH = 14.

Question 32

How do you find the pH of a weak base?

Answer 32

Use the formula pH = 14 - pOH, and calculate pOH using Kb.

Question 33

What does Kb represent?

Answer 33

Kb represents the base dissociation constant.

Question 34

In a strong acid-strong base reaction, what is the pH of the resulting solution?

Answer 34

The pH of the resulting solution is typically 7.

Question 35

How do you calculate pH for a weak acid?

Answer 35

Use the formula pH = -log[H+] and calculate [H+] from Ka.

Question 36

What does Ka stand for?

Answer 36

Ka stands for the acid dissociation constant.

Question 37

True or False: Strong bases do not affect the pH of a solution.

Answer 37

False.

Question 38

What is the formula for calculating the concentration of [H+] from a weak acid?

Answer 38

Use the formula [H+] = sqrt(Ka * [HA]).

Question 39

What happens to pH when a strong acid is added to a weak base?

Answer 39

The pH decreases significantly.

Question 40

What is the effect of dilution on the pH of a strong acid?

Answer 40

Dilution increases the pH (makes it less acidic).

Question 41

Fill in the blank: A solution with a pH of 3 is ___

Answer 41

acidic.

Question 42

How does temperature affect pH?

Answer 42

Temperature changes can affect the ionization of water and thus the pH.

Question 43

What is the pH of a 0.1 M NaOH solution?

Answer 43

The pH is approximately 13.

Question 44

What is the formula to find the pH of a buffer solution?

Answer 44

The Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]).

Question 45

True or False: A buffer solution can resist changes in pH upon the addition of small amounts of acid or base.

Answer 45

True.

Question 46

What is the pH of a solution at the equivalence point of a weak acid-strong base titration?

Answer 46

The pH is greater than 7.

Question 47

How do you calculate the pH at the equivalence point of a weak base-strong acid titration?

Answer 47

Calculate the pH using the concentration of the conjugate acid formed.

Question 48

What is the importance of knowing the pH of a solution?

Answer 48

Knowing the pH is essential for understanding the chemical behavior and reactivity of the solution.

Question 49

What is the effect of a strong acid on the pH of a weak acid solution?

Answer 49

It lowers the pH, making the solution more acidic.