Chpt 17: Additional Aspects of (Aq) Equilibria

Question 1

what is the k constant expression for complex ions called (in words)

Answer 1

formation constant

Question 2

are the metal cations in complex ions Lewis acids or Lewis bases?

Answer 2

Lewis acids

Question 3

Are common ion solutions examples of buffered solutions?

Answer 3

yes

Question 4

how much of the metal in a metal salt gets consumed to make complex ions?

Answer 4

all of it. assume all of it is consumed.

Question 5

what 4 ions make compounds that can become more soluble in acidic or basic solutions 2o to being amphoteric?

Answer 5

oxides and hydroxides of Al3+, Cr3+, Zn+, and Sn+

Question 6

What are 3 suitable Lewis Bases for making complex ions?

Answer 6

CN-, OH-, NH3

Question 7

true or false: when you add a component to a rxn in equilibrium, the rxn will shift to re-establish equilibrium, but the concentration of the component that was added to will never drop below its original concentration.

Answer 7

true

Question 8

when solving for pH (or similar) in a buffer problem, when can you ignore a bunch of the x values in the Ka expression?

Answer 8

when you have a common ion situation and the ka is small

Question 9

In instances where you have multiple rxns occurring at once/together, Is the ‘x’ that represents molar solubility given by the value from the ksp expression or the value from the ICE table?

Answer 9

the value from the ICE table.

If one rxn, use ksp
If multiple rxns, use ICE table and New K value that calculated from combining the multiple rxns

Question 10

True or false: a weak acid can be more concentrated than a strong acid?

Answer 10

True (if you have more weak acid than strong acid)

exp. 20M HF is more concentrated than 10M HCl. The strength is not a factor in how concentrated the acid is

Question 11

if you’re asked to find the molar solubility for a solid in an instance where 2 different reactions are happening simultaneously/able to be combined into a single net rxn which should you use to find the answer: the solid’s ksp expression or the K expression for the net rxn (along with relevant concentrations from an ICE table)

Answer 11

K expression for the net rxn (along with relevant concentrations from an ICE table)

multiple reactions/solids require the multiple rxns to be combined. This gives a new K that has it’s own k expression

Question 12

are complex ions soluble in water?

Answer 12

very. To tell how much, you have to look at the Kf

Question 13

in complex ion problems, how important is it to know the phases of the species?

Answer 13

VERY!!! You need to know which things to omit from the relevant ICE tables and/or k expressions

Question 14

if you have a metal salt in solution with Lewis base, what two reactions can you expect are taking place?

Answer 14

1. rxn for the dissolution of the metal salt (bc the Lewis base makes it more soluble); will have a ksp
2. rxn where the ions from the salt bind with the Lewis base to make the complex ion; will have a Kf

These get combined together to make a net chemical equation, which has its own ‘new’ K

Question 15

how does the formation of complex ions impact a metal salts’ solubility?

Answer 15

they greatly increase its solubility

aq reactions that produce complex ions will trump all other aq rxns happening in the same beaker a

Question 16

when conditions are right to ignore x values in a buffer’s Ka expression, which x values can you ignore?

Answer 16

All of them except for the one associated with [H+]

Question 17

what does it mean to titrate something?

Answer 17

when you slowly add one thing (a titrant) to a known volume of another thing (with unknown concentration) until the reaction reaches NEUTRALIZATION

Question 18

what is a complex ion, anyway?

Answer 18

what you call it when a substance in a solution acts like a Lewis base and causes metals (especially transition metals) to bind to it

a metal bound to a substance that is acting as a Lewis base

Question 19

what enables a buffer to withstand the addition of larger and larger amounts of added acid/base?

Answer 19

large concentrations of the weak acid/base and conjugate in the buffer

Question 20

what is buffer capacity?

Answer 20

the amount of added acid/base that a buffer can neutralize before it gets overwhelmed and stops being able to resist pH changes

Question 21

When you titrate something (bring one reactant/solution to neutralization with another reactant/solution), what does it mean to say that you’ve achieved neutralization?

Answer 21

It means that the moles of the two reactants/solutions are stoichiometrically equal

Question 22

when might you have to reverse your complex ion reaction/flip your Kf?

Answer 22

if the problem asks you for the concentration or molar solubility of one of the reactants for the complex ion

when you’ve been asked to treat the complex ion like a reactant instead of a product

Question 23

are complex ions aq or solid?

Answer 23

aq

Question 24

what is a Salt?

Answer 24

the ionic compound that makes ions in solution

Question 25

What is the other name for the ‘neutralization point in a titration?’

Answer 25

equivalence point

Question 26

when solving for a ksp, why does the rxn equation have to be balanced?

Answer 26

because stoichiometric coefficients are included in the ksp expression

Question 27

what is the Common Ion Effect

Answer 27

a shift in equilibrium induced by an ion common to the equilibrium.

Question 28

what are the 2 ways you can have a buffer?

Answer 28

1. by having a weak acid or base present with its conjugate

2. by having a strong acid or base with an EXCESS amount of weak acid or base