Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

flashcards! > Ap Chem. Ch. 17 > Flashcards

Ap Chem. Ch. 17 Flashcards

0
Q

What are buffers?

A

Solutions of a weak conjugate acid-base pair.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

What does the common-ion effect state?

A

A weak electrolyte will ionize less when a strong electrolyte with a common ion is added to the solution.
Ex: +
CH3COOH + H2OH3O + CH3COO-
-if NaCH3COO is added, the acetic acid will ionize less!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Buffers are resistant to pH changes, even when strong acid or base is added, why?

A

Because it contains both an acid to neutralize OH- ions and a base to neutralize H+ ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are three ways of making buffers?

A
  1. by mixing a weak acid or weak base with a salt
  2. by partial neutralization of a weak acid with a strong base.
  3. by partial neutralization of a conjugate base from a salt
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

3 factors that affect the solubility of ionic compounds:

A
  1. presence of common ions
  2. the pH of the solution
  3. the presence of complex agents
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When a small amount of OH- is added to the buffer (HXH+ + X-), the OH- reacts with HX to produce X- and water. What happens to the [HX]/[X-] ratio and pH?

A

The [HX]/[X-] ratio remains more or less constant, so the pH is not significantly changed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When a small amount of [H+] is added to a buffer ( HX H+ + X- ), X- is consumed to produce HX. What happens to the ratio of [HX]/[X-] and pH?

A

Their ratio is more or less constant, so the pH does not change significantly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Henderson-Hasselbalch equation

A

PH= pKa + log[base/acid]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

At [base]=[acid],

pH?pKa

A

pH=pKa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

At [base]<[acid]

pH?pKa

A

pH<pKa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

[base]>[acid]

pH?pKa

A

pH>pKa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When do buffers resist a change in pH in either direction ?

A

If the weak acid and its conjugate base are equimolar.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In this technique a known concentration of base(or acid) is slowly added to a solution of acid(or base).

A

Acid-base titrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Titration of a strong acid with a strong base:
1. At the start the pH is determined by the acid.(no base has been added)
What equation is used?

A

pH=-log[acid]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Titration of a strong acid with a strong base.
2.after the start of the titration to near the equivalence point, the pH goes up slowly(when adding base). What equation is used?

A

[H+]=(mol H+) - (mol OH-)/total volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Titration of a strong acid with a strong base:
3.at the equivalence point, moles acid=moles base, and the solution only contains water and the salt from the cation of the strong base and the anion of the strong acid.

A

PH=7

16
Q

Titration of a strong acid with a strong base

4. As more base is added, the increase in pH again levels of (excess base). What is the equation?

A

[OH-]=(mol OH-) - (mol H+)/total volume

17
Q

Titration of a Weak Acid with a strong base. Three things to remember!

A
  1. the conjugate Base of the acid affects the pH when it is formed.
  2. At the equivalence point the pH>7
  3. Phenolphthalein is commonly used as an indicator in these titrations.
18
Q

Titration of a Weak Acid with a strong base.

1.at the start, the pH is determined by the concentration of the weak acid and Ka.what equation is used?

A

Ka= x^2/ HA-x (just a normal Ka problem)

19
Q

Titration of a Weak Acid with a strong base.
2.Between the initial pH and the equivalence point, a partial neutralization creates a buffer solution.
What equation is used?(half equivalence point. [HA]=[A-] and pH=pKa)

A

Find the[HA] and the [A-] and use Henderson-Hasselbalch to calculate

20
Q

At what point during the titration should the indicator change color?

A

At the equivalence point

21
Q

Titration of a Weak Acid with a strong base.
3. At the equivalence point, the H+ and OH- neutralize each other, but the weak base, [A-] WILL CAUSE THE SOLUTION TO BE SLIGHTLY BASIC. What equation should you use?

A

Use the Kb of the weak base,[A-], to calculate the pH.

22
Q

Titration of a Weak Acid with a strong base.
4. After the equivalence point, the weak base contribution is NEGLIGIBLE, compared to the [OH-].
What equation is used?

A

[OH-] = (mol OH-) - (mol H+)/ total volume

23
Q

When one titrates a polypeptide acid with a base, there is an __________ for each dissociation.

A

Equivalence point

24
Q

Solubility product

A

Ksp

25
Q

What does the common-ion effect do to the solubility of a weak electrolyte?

A

The presence of a common ion reduces the solubility equilibrium of the weak electrolyte, shifting the solubility equilibrium of the weak electrolyte to the left.

26
Q

The pH of a solution will affect the solubility of any substance whose anions is _____.

A

Basic

27
Q

If a compound contains a basic anion( the anion of a weak acid), what will happen to its solubility as the solution becomes more acidic?

A

It’s solubility will increase

28
Q

The solubility of slightly soluble salts containing basic anions increases as what increases?

A

[H+] increases(as pH is lowered)

29
Q

The more basic the anion, the more the solubility is influenced by what??

A

pH

30
Q

Slats with anions of strong acids are _______ by pH changes.

A

Unaffected

31
Q

Characteristic property of metal ions:

A

Their ability to act as Lewis Acids, or electron-pair acceptors, toward water molecules that act as Lewis Bases or electron-pair donors

32
Q

General rule of complex ions: the solubility of metal salts increases in the presence of _______ such as NH3,CN-, or OH-, if the metal forms a complex with the base.

A

Lewis bases

33
Q

Amphoteric oxides and hydroxides:

A

These substances are soluble in strong acids and strong bases because they themselves are capable of behaving as either an acid or a base

34
Q

Example of Amphoteric oxides and hydroxides:

A

Al3+,Cr3+, Zn2+, and Sn2+

35
Q

If Q=Ksp the system is at ________ and the solution is saturated.

A

Equilibrium

36
Q

If the Q<Ksp , the solid…..

A

Dissolves until Q=Ksp

37
Q

If Q>Ksp, the salt will…

A

Precipitate until Q=Ksp

flashcards! (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions