FINAL study guides Flashcards
A spontaneous reaction implies…
- ΔK > 1
- ΔG < 0
- ΔSuniverse > 0
- E∅ > 0
- NOT: ΔHrxn < 0
What does normal boiling pt / normal freezing pt signify?
Normal ⇒ 1 atm pressure
When does boiling occur (regarding the vapor pressure of the liquid)?
When vapor pressure (v. p.) of liquid equals external pressure
- for normal boiling point: Vpressure = 1 atm.
- ΔHvap = P
What are “standard conditions”?
- 1 M aqueous species
- P = 1 atm
dissolution (solubility/ionization) reaction
solid <–> aq + aq
- ex: AgI (s) <–> Ag+ (aq) + I- (aq)
- ex: Fe(OH)3 (s) <–> Fe3+ (aq) + 3(OH-) (aq)
dissolution (solubility/ionization) reactions can go in ___ direction(s)
forwards and backwards directions
<—–>
precipitation reaction
(aq) + (aq) –> solid
- Ag+ (aq) + I- (aq) –> AgI (s)
- Fe3+ (aq) + 3(OH-) (aq) –> Fe(OH)3 (s)
precipitation reactions go in __ direction(s)
ONLY forwards direction
—–>
water auto-ionization reaction (water dissociation reaction)
H2O (l) <—> H+ (aq) + OH- (aq)
- Kw = 1 x 10^14 @ 25C
will a buffer form?
CA/CB in comparable amounts
- if not comparable, do SICE table
SA/WB or WA/SB, SICE, CA/CB in comparable amounts?
is the aqueous solution (compound) acidic?
1) cancel out ions from SA/SB
2) are the remaining ions cations (+) or anions (-)?
- cations (+) = acidic
- anions (-) = basic
acid with smallest pKa corresponds to the _____ with largest ____ because pKa + pKb = 14 for conjugates.
- conjugate base
- pKb
The larger the pK value, the ___ that species is
- weaker
pH at equivalence point of SA/SB
pH = 7
pH at equivalence point of a SB/ WA
pH > 7
pH at equivalence point of SA/WB
pH < 7
∆G = 0…
- at phase transition
- at equilibrium
- Q = K
- boiling
- ∆H = T∆S
For an exothermic reaction…
reaction loses heat –> ∆Hrxn < 0
entropy of surrounding ↑ –> ∆Ssurr > 0
boiling point increases w/ increasing…
- increasing molar mass
- increasing polarity
- increases greatly w/ hydrogen bonding
What are the general properties of a water-soluble molecule or ion?
- monovalent charge (charge = ±1)
- presence of polar bonds
- if “long; several hydroxyl groups (OH) throughout
- number of carbons ≤ 5 (linear chain)
- heterocyclic rings ( nitrogen or oxygen as well as carbons at vertices of hexagon)
SO3 gas dissociation reaction:
2 SO3 (g) → 2 SO2 (g) + O2 (g)
if a question asks about a “shift in equilibrium”, you need…
K and Q and to compare
(multi-step reaction energy plot): the rate-limiting step usually…
involves the larger activation energy “barrier”
- largest Ea / largest “hump”
(multi-step reaction energy plot): How many transition states are involved?
how many humps on the graph
