Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
42 Cards in this Set
- Front
- Back
|
Equilibrium Expression (how to write) |
aA + bB <--> cC + dD
K = ([C]^c)([D]^d) / ([A]^a)([B]^b) |
|
|
What's not included in an equilibrium expression? |
solids and liquids |
|
|
Conceptual meaning of K |
if K > 1, the reaction favors the products (more products present at equilibrium)
if K < 1, the reaction favors the reactants (more reactants present at equilibrium) |
|
|
K and spontaneity |
If K > 1 (spontaneous) If K < 1 (non spontaneous) |
|
|
If a reaction is reversed, what happens to K? |
you get the inverse of it (1/K) |
|
|
if a reaction is double (coefficients doubled), what happens to K? |
you square K (ex: K^2) |
|
|
Weak acids (and Ka) |
partially dissociate
Ka is much less than 1 (Ex: x 10^-??) |
|
|
Strong Acids |
HCl HBr HI HNO3 H2SO4 HClO4 |
|
|
Strong Acids definition |
completely dissociate (K >1) |
|
|
How to calculate pH of a strong acid |
-log[H+]
and [H+] = [acid] |
|
|
How to calculate pH of a weak acid |
Use ICE table |
|
|
What species are present in greatest concentration in a weak acid? |
HA since it only partially dissociates
HA <--> H+ + A- |
|
|
What species are present in greatest concentration in a strong acid? |
A- and H+ since it only partially dissociates
HA <--> H+ + A- |
|
|
how are Ka and Kb related? |
Ka * Kb = Kw
(on your equation sheet) |
|
|
Le Chatelier's principle |
allows us to predict how a reaction will shift when stressed qualitatively |
|
|
Le Chatelier and Pressure
If P increases, then reaction shifts... |
towards side with less moles of gas |
|
|
Le Chatelier and Pressure
If P decreases, then reaction shifts... |
towards side with more moles of gas |
|
|
If Q > K |
reaction shifts left |
|
|
If Q < K |
reaction shifts right |
|
|
If Q = K |
the reaction is at equilibrium |
|
|
Ksp |
solubility product |
|
|
If Ksp is a large value then...
If Ksp is a small value then... |
the substance dissolves a lot
the substance dissolves a little |
|
|
Bronsted-Lowry Acid/Base |
Acid: donates a H+ Base: accepts an H+ |
|
|
Conjugate Acid |
what a base becomes after it GAINS an H+ |
|
|
Conjugate Base |
what an acid becomes after it LOSES an H+ |
|
|
Bronsted-Lowry acid/conj base pair |
H2CO3 + H2O <--> H3O^+ + HCO3^-
Acid/conj base pair: H2CO3 and HCO3^-
Base/conj acid pair: H2O and H3O^+ |
|
|
pH |
a measure of the [H+]
=-log[H+] |
|
|
pOH |
a measure of the [OH-]
=-log[OH-] |
|
|
pH and pOH relationship |
pH + pOH = 14 |
|
|
Polyprotic Acid |
an acid with more than 1 H to donate
H2CO3 H2SO4 H3PO4
NOT: HNO3
|
|
|
Titration |
experimental technique where acid/bases are mixed to determine the concentration of one or the other |
|
|
Strong Acid + Strong Base titration |
pH at equivalence point = 7 |
|
|
Strong Acid + Weak Base titration |
pH at equivalence point < 7 |
|
|
Strong Base + Weak Acid titration |
pH at equivalence point > 7 |
|
|
Midpoint (Half-equivalence point) |
occurs when half the volume needed to get to the equivalence point has been added
at this point, [HA] = [A-] and pH = pKa
"concentration of weak acid = concentration of conj base" |
|
|
Equivalence Point |
moles of acid = moles of base |
|
|
how to calculate pKa |
=-log(Ka) |
|
|
Species present in greatest concentration BEFORE midpoint |
HA |
|
|
Species present in greatest concentration AT midpoint |
HA and A- (equal) |
|
|
Species present in greatest concentration AFTER midpoint but before equivalence point |
A- |
|
|
Buffer |
a substance that resist changes in pH (made of a weak acid and its conj base)
Ex: HC2H3O2 + NaC2H3O2 |
|
|
How to determine best buffer for a specific pH range? |
use the exponent of the pKa
Ex: if pKa of acid is 5 x 10^-4
this would be best used as a buffer around pH = 4 |
