Gibbs Free Energy
What set of conditions would make a reaction spontaneous at all temperatures?
ΔH would be _____ (positive or negative?)
ΔS would be _____ (positive or negative?)
Mother Nature likes...
ΔH = negative = exothermic
ΔS = positive =chaotic
Electrons in a battery flow in which direction?
a) anode to cathode
b) cathode to anode
c) depends on the type of cell
Anode to Cathode (always "ABC")
At equilibrium, what exactly is it that is equal?
The rate of the forward reaction relative to the reverse reaction
In an exothermic reaction, which change would cause the reaction to shift to the right (forwards)?
a) increase temperature
b) decrease temperature
c) add a catalyst
decrease temperature
An endothermic reaction occurring in a beaker will feel _____ to the person holding the beaker.
a) hot
b) cold
c) no change in temp
Cold
When using Δ GO = ─RTln(K), the value for R is...
a) 0.08206
b) 273
c) 8.314
8.314
In a galvanic cell, the reduction occurs at
a) the anode
b) the cathode
c) the salt bridge
Reduction ALWAYS occurs at the cathode (always RedCat)
Which of the following is the least soluble?
AgBr (Ksp = 7.7x10-13)
PbCl2 (Ksp = 1.6x10-5)
Li3PO4 (Ksp = 2.4x10-4)
AgBr (Ksp = 7.7x10-13)
Which direction will it shift if the volume is increased?
2 X(s) + 3 Y(g) ⇌ 2 Z(g) + 2 W(g)
towards more moles of gas (in this case, shifts right).
The enthalpy, ΔH, for an exothermic reaction would be
a) positive
b) negative
c) zero
At equilibrium, ΔG is...
a) greater than zero
b) less than zero
c) equal to zero
equal to zero
In the equation ΔGO=-nFE, what does n refer to?
number of electrons transferred
Write the equilibrium expression for the following:
X(s) + 2Y(aq) ⇌ Z(aq)
[Z]/[Y2]
If the K value for a given reaction is 2/5, what would be the K value of the reverse reaction.
5/2
Energy is stored in bonds. To calculate the bond enthalpy what mathematical operation is used?
a) reactants minus products
b) products minus reactants
c) products over reactants
d) reactants over products
products minus reactants
If ΔGO is negative, then EOcell is ...
a) positive
b) negative
c) zero
positive
While a battery is running, the mass of the cathode will...
a) increase
b) decrease
c) stay the same
increase
If K is less than 1, the concentration of _____ is higher at equilibrium.
a) products
b) reactants
reactants
If Q is larger than K, which direction will the reaction run to achieve equilibrium?
a) forwards
b) backwards
c) no shift
backwards because K<Q means <--
What are the most common units for ΔH and ΔS?
ΔH is usually in kilojoules (kJ/mol)
ΔS is usually in Joules (J/mol⋅K)
As Gibbs Free Energy, ΔG, decreases (becomes more negative), does the value of K...
a) increase
b) decrease
c) remain the same
Name two specific differences between a Galvanic and a Electrolytic Cell.
1) Galvanic has 2 beakers, electrolytic has 1
2) Galvanic produces Volts, electrolytic uses Volts
3) Galvanic uses aqueous, electrolytic uses liquid
4) Charges on their electrodes are opposite
When writing out the K expression, which states of matter are kept (vs omitted)?
Keep aqueous and gas; omit solids and liquids
If a dirty beaker already has OH- residue present, solid Ca(OH)2 will have an more difficult time dissolving than it already does. What is the name of this phenomenon?
The Common Ion Effect (Le Chatlier's principle is also correct but not as specific)
Breaking bonds is ____ (exothermic/endothermic).
Forming bonds is ____ (exothermic/endothermic).
Breaking bonds requires energy (endo)
Forming bonds releases energy (exo)