LO 59 - 65

Question 1

What is a titration?

Answer 1

Acid or base of unknown concentration is neutralized with an acid/base of known concentration

Question 2

What is the equivalence point of a titration?

Answer 2

Point in which the number of mols of base is stoichiometrically equal to the number of mols of acid

Question 3

The equivalence point of a strong acid + strong base titration is always pH = ____

Answer 3

7.0

Question 4

[H30+] before the equivalence point of a SA + SB titration is calculated by . . .

Answer 4

Since [H30+] is in excess before the eq.
[H30+] = (mol H30 initial - mol OH added)/total volume

Question 5

[OH-] after the equivalence point of a SA + SB titration is calculated by . . .

Answer 5

Since [OH-] is in excess after the eq.
[OH-] = (mol OH added - mol H3O initial)/total volume

Question 6

What are the 5 steps to titrating a weak acid of unknown concentration with a strong base?

Answer 6

1. Find the volume strong base needed to reach EQ using V1M1=V2M2
2. Find the initial H3O+ concentration from initial pH
3. Set up a Δmols table where the desired amount of OH- reacts with the weak acid to form H2O and the conjugate base (buffer)
4. Use HH equation to find buffer pH from additions
5. At equilibrium only conjugate base is left so calculate pH using an equilibrium problem as it ionizes with H2O

Question 7

When pH=pKa of a buffer solution as more strong base is added to a weak acid, you’re . . .

Answer 7

halfway to the equivalence point

Question 8

A = log(X) can be canceled out by . . .

Answer 8

A = log(X) –> 10^A = X

Question 9

When titrating a weak acid with a strong base the eq. point will have a slightly ________ pH

Answer 9

basic

Question 10

When titrating a weak base with a strong acid the eq. point will have a slightly ________ pH

Answer 10

acidic

Question 11

When titrating a weak base with a strong acid the pKa in the HH equation corresponds to . . .

Answer 11

the conjugate acid of the weak base that is being titrated

Question 12

When titrating polyprotic acids with sufficiently different Ka1 and Ka2, the pH curve will have . . .

Answer 12

2 equivalence points

Question 13

pH indicators are commonly . . .

Answer 13

weak organic acids

Question 14

With an indicator, we rely on the point when there is a change in color known as the _________ to determine the eq. point

Answer 14

endpoint

Question 15

The _____________ is the equilibrium expression of a chemical equation representing the dissolution of a slight to moderately soluble ionic compound

Answer 15

solubility product constant (Ksp)

Question 16

__________ is the solubility of a compound in units of mols per L

Answer 16

molar solubility

Question 17

The relationship between Ksp and molar solubility depends on . . .

Answer 17

the stoichiometry of the dissociation reaction

Question 18

What are Ksp and molar solubility comparable to in calculation?

Answer 18

A RICE table in which the rxn is the dissociation reaction, Ksp is the K value, and molar solubility is the x value

Question 19

What is the result of the common ion effect?

Answer 19

Generally, the solubility of an ionic compound is LOWER in a solution containing a common ion than it would be in H2O

Question 20

The solubility of an ionic compound with a strong or weak basic anion __________ with increasing acidity (lower pH)

Answer 20

Increases

Question 21

Given an ionic compound with a strong or weak basic anion in a solution with a high pH, what happens to the dissociation reaction?

Answer 21

If the pH is high there is more OH - in solution (product), shifting the dissociation reaction left, lowering solubility

Question 22

Given an ionic compound with a strong or weak basic anion in a solution with a low pH, what happens to the dissociation reaction?

Answer 22

If the pH is low there is more H3O+ in solution (reactant with the OH- produced), shifting the dissociation reaction right, increasing solubility

Question 23

When calculating the molar solubility of an ionic compound in a common ion solution, what do you need to remember about the RICE table?

Answer 23

That the produced ion will NOT be 0 initially but rather be equal to the concentration of the same ion already in solution

Question 24

Q < Ksp

Answer 24

solution is unsaturated and more solid ionic compound can dissolve

Question 25

Q = Ksp

Answer 25

solution is saturated and is holding the EQ amount of dissolved ion. added solid will not dissolve

Question 26

Q > Ksp

Answer 26

the solution is supersaturated and under most circumstances will precipitate excess solid

Question 27

_____________ is the process in which the addition of a reagent will form a precipitate with one select cation of those in solution

Answer 27

selective precipitation