Redox reactions
What oxidation number will elements in group 2 usually have?
+2
Oxidation is the ______ of electrons and reduction is the ______ of electrons
loss, gain
In a galvanic cell, the anode has a ______ charge and will _____ mass as the reaction proceeds.
Negative, Lose
Which of the following is the strongest reducing agent?
a) Ered = -1.22
b) Ered = + 0.87
c) Ered = -0.05
d) Ered = + 1.6
a) Ered = -1.22
What are the five most populous metro areas in Oregon?
Portland, Salem, Eugene, Bend, Medford
What is the oxidation number for (C) in C2O42− and CO?
+3 in C2O42− and +2 in CO
Summarize the steps for assigning oxidation numbers in compounds
Approximate covalent bonds as ionic, give electrons to more electronegative partner in a given bond, assign oxidation states like normal.
What is the Ecell for a galvanic cell containing a silver electrode submerged in aqueous Ag+ and a titanium electrode submerged in aqueous Ti2+?
2.43V
A large K value corresponds with reactants favored or products being favored?
Products are favored
What products does Oregon produce more of than any other state?
Hazelnuts and christmas trees
In which one of the following molecules does sulfur have the smallest oxidation number?
a) SO3
b) SO42-
c) S2O32-
d) SO2
S2O32-
Does a large K value correspond with a positive or negative Ecell?
Positive Ecell
A voltaic cell consists of one half-cell that contains Ag(s) and Ag+(aq), and one half-cell that contains Pb(s) and Pb2+(aq). What species are produced at the electrodes under standard conditions?
Ag+(aq) + e- → Ag(s) E° = +0.80 V
Pb2+(aq) + 2 e- → Pb(s) E° = -0.13 V
Ag(s) is formed at the cathode, and Pb2+(aq) is formed at the anode.
Using the standard reduction potential table which of the following is the weakest oxidizing agent?
a) Mg2+
b) Na+
c) F2
d) PbO2
b) Na+
What is Oregon's highest peak, and how tall is it?
Mount Hood—11,249ft
When the redox reaction below is balanced in acidic solution, how many electrons “cancel out” in the overall equation?
Cr2O72- (aq) + I- (aq) —→ 2Cr3+ (aq) + I2 (aq)
6 electrons
How many moles of hydroxide are there in the balanced equation of the following reaction(what's the coefficient on OH):
As2O3(s) + NO3-(aq) → AsO43-(aq) + NO(g)
14
Which statement is true for a galvanic cell constructed from the two half-reactions below?
Half-reaction Ered∘ (V)
Ag+ (aq) + e - → Ag(s) +0.80
Zn2+(aq) + 2e-→ Zn(s) –0.76
a) Zn2+ is reduced at the cathode; Ecell = +0.44 V
b) Ag+ is reduced at the cathode; Ecell = +1.56 V
c) Ag(s) is oxidized at the anode; Ecell = +0.80 V
d) Zn(s) is reduced at the cathode; Ecell = +1.56 V
b) Ag+ is reduced at the cathode; Ecell = +1.56 V
A reaction involves the transfer of 2 electrons. E°cell = +0.154V.
What is the value of the equilibrium constant, K, for this reaction?
K = 1.62 x 105
Western Meadowlark
When the redox reaction below is balanced in basic solution, how many water molecules are in the overall equation?
MnO4- + C2O4-2 → Mn2++ CO2
8 H2O
What element is undergoing oxidation in the following reaction?
2 MnO4-(aq) + 3 NO2-(aq) + H2O(l) → 2 MnO2(s) + 3 NO3-(aq) + 2OH-(aq)
Nitrogen
Find Ecell if the number of electrons transfered in the reaction is 1 and the equillibrium constant is 9.0617*1019
Ecell = 1.18V
Find the equilibrium constant for the following unbalanced redox reaction at 25ºC:
As2O3(s) + NO3-(aq) → AsO43-(aq) + NO(g)
Standard reduction potentials:
As2O3(s) → AsO43-(aq) +0.57 V
NO3 (aq) → NO (g) +0.96 V
n = 12e-
Use ln(k) = (nf/RT) *Ecell (and don't forget that this is one term with Ecell in the numerator)
K = 1.42 *1079
What's special about the US 30 from the Dalles to Portland?
It was the first scenic highway in the United States