Chapter 17 - Aqueous Equilibria

Question 0

Henderson hasselbach eqn

Answer 0

pH = pKa + log ([base]/[acid])

Question 1

Buffers

Answer 1

Solutions of a weak conjugate acid-base pair

Resistant to pH changes even when strong acid or base is added

Question 2

pH range

Answer 2

The range of pH values over which a buffer system works effectively

Best to choose an acid with a pKa close to desired pH

Question 3

Addition of strong acid or bad to a buffer steps

Answer 3

1. Determine how the neutralization reaction affects the amount of the weak acid and its conjugate base in solution
2. Use ran to determine new pH

Question 4

Titration

Answer 4

A known concentration of base or acid is slowly added to acid or base

pH meter indicated when solution has reached equivalence point

Question 5

Equivalence point

Answer 5

Moles of acid equal miles of base

Solution contains only water and salt from cation of base and anion of acid

Question 6

Titration of a weak acid with a strong base

Answer 6

Eq pt the pH is greater than 7

Phenolphthalein is a common indicator

Initial pH is higher and changes near equiv pt are more subtle

Question 7

Below equivalence point

Answer 7

pH of solution is determined from the amounts of the acid and its conjugate base present

Question 8

Titration of weak base with strong acid

Answer 8

pH is less than seven at eq pt

Methyl red is indicator

Question 9

Polypeptides acid titration

Answer 9

Eq point for each dissociation

Question 10

Solubility product

Answer 10

Ksp
Not same as solubility

Affected by:
The common ion effect
pH
Complex ions
Amphoterism

Question 11

Factors affecting solubility (the common ion affect)

Answer 11

If one of the ions in a solution equilibrium is already dissolved in be solution the equilibrium will shift left and the solubility of the salt will decrease

Question 12

Factors affecting solubility (pH)

Answer 12

If a substance has a basic anion it will be more soluble in an acidic solution

Substances with acidic cations are more soluble in basic solutions

Question 13

Factors affecting solubility (complex ions)

Answer 13

Metal ions can act as Lewis acids and form completely ions with Lewis bases in the solvent

The formation of these complex ions increases solubility of these salts

Question 14

Factors affecting solubility (amphoterism)

Answer 14

Amphoteric metal oxides and hydroxides are soluble in strong acid or base because they can act as either

Ex: Al Zn Sn

Question 15

If Q = Ksp

Answer 15

The system is at equilibrium and the solution is saturated

Question 16

If Q < Ksp

Answer 16

More solid can dissolve until they are equal

Question 17

If Q > Ksp

Answer 17

The salt will precipitate until equilibrium

Question 18

How can one separate ions in a mixture?

Answer 18

Use differences in solubilities of salts

Question 19

When strong acids or bases are added to a buffer

Answer 19

Assume all acid or base is consumed
ICE table in moles
Henderson hasselbach eqn