Chpt 17: Additional Aspects of (Aq) Equilibria Flashcards
what is the k constant expression for complex ions called (in words)
formation constant
are the metal cations in complex ions Lewis acids or Lewis bases?
Lewis acids
Are common ion solutions examples of buffered solutions?
yes
how much of the metal in a metal salt gets consumed to make complex ions?
all of it. assume all of it is consumed.
what 4 ions make compounds that can become more soluble in acidic or basic solutions 2o to being amphoteric?
oxides and hydroxides of Al3+, Cr3+, Zn+, and Sn+
What are 3 suitable Lewis Bases for making complex ions?
CN-, OH-, NH3
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.
true
when solving for pH (or similar) in a buffer problem, when can you ignore a bunch of the x values in the Ka expression?
when you have a common ion situation and the ka is small
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?
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
True or false: a weak acid can be more concentrated than a strong acid?
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
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)
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
are complex ions soluble in water?
very. To tell how much, you have to look at the Kf
in complex ion problems, how important is it to know the phases of the species?
VERY!!! You need to know which things to omit from the relevant ICE tables and/or k expressions
if you have a metal salt in solution with Lewis base, what two reactions can you expect are taking place?
- rxn for the dissolution of the metal salt (bc the Lewis base makes it more soluble); will have a ksp
- 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
how does the formation of complex ions impact a metal salts’ solubility?
they greatly increase its solubility
aq reactions that produce complex ions will trump all other aq rxns happening in the same beaker a
when conditions are right to ignore x values in a buffer’s Ka expression, which x values can you ignore?
All of them except for the one associated with [H+]
what does it mean to titrate something?
when you slowly add one thing (a titrant) to a known volume of another thing (with unknown concentration) until the reaction reaches NEUTRALIZATION
what is a complex ion, anyway?
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
what enables a buffer to withstand the addition of larger and larger amounts of added acid/base?
large concentrations of the weak acid/base and conjugate in the buffer
what is buffer capacity?
the amount of added acid/base that a buffer can neutralize before it gets overwhelmed and stops being able to resist pH changes
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?
It means that the moles of the two reactants/solutions are stoichiometrically equal
when might you have to reverse your complex ion reaction/flip your Kf?
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
are complex ions aq or solid?
aq
what is a Salt?
the ionic compound that makes ions in solution
What is the other name for the ‘neutralization point in a titration?’
equivalence point
when solving for a ksp, why does the rxn equation have to be balanced?
because stoichiometric coefficients are included in the ksp expression
what is the Common Ion Effect
a shift in equilibrium induced by an ion common to the equilibrium.
what are the 2 ways you can have a buffer?
- 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
