Chapter 18 – Electrochemistry
128.
Write the formula of the weakest reducing agent given the following standard reduction potentials in acid solution:
129.
Write the formula of the strongest reducing agent given the following standard reduction potentials in acid solution:
Chapter 18 – Electrochemistry
130.
Write the formula of the strongest oxidizing agent given the following standard reduction potentials in acid solution:
131.
Select True or False: The balanced equation for a spontaneous reaction which involves the tin and zinc redox couple using
the following standard reduction potentials in acid solution is:
Zn + Sn4+ → Zn2+ + Sn2+
Chapter 18 – Electrochemistry
132. Calculate Ecell for the following electrochemical cell:
Ni(s) | Ni2+(aq) || Hg22+(aq) | Hg(l) | Pt(s)
133. Calculate Ecell for the following electrochemical cell:
Mn(s) | Mn2+(aq) || Ce4+(aq),Ce3+(aq) | Pt(s)
Chapter 18 – Electrochemistry
134.
Calculate G (kJ/mol) for the following electrochemical cell:
Be(s) | Be2+(aq) || Mn2+(aq)| Mn(s)
135.
Calculate G (kJ/mol) for the following electrochemical cell:
Cd(s) | Cd2+(aq) || Ni2+(aq)| Ni(s)
Chapter 18 – Electrochemistry
136.
Determine the equilibrium constant for the following reaction at 25C.
2I– (aq) + Br2(l) I2(s) + 2Br–(aq).
137.
Determine the equilibrium constant for the following reaction at 298 K.
2Fe3+(aq) + H2O2(aq) 2H+(aq) + O2(g) + 2Fe2+(aq).
Chapter 18 – Electrochemistry
138. If the cell emf of a Zn–Cu cell is 0.80 V when the concentration of Zn2+ is 2.0 M, what is
the concentration of Cu2+?
139. Aluminum metal is formed by the electrolysis of Al2O3 in molten cryolite. How many
grams of Al are produced when 6.50 103 C pass through the cell?
Chapter 18 – Electrochemistry
140. Aluminum metal is formed by the electrolysis of Al2O3 in molten cryolite. How many
minutes are required to form 10.0 g of Al using a current of 30 A?
141. How many moles of H2 are produced by 5.00 A of current passing through a cell
containing aqueous NaCl for 4.00 102 s?
Chapter 18 – Electrochemistry
142. What concentration of Ni2+ ion remains in solution after electrolysis of 100. mL of 0.250
M NiSO4 solution when using a current of 2.40 amperes for 30.0 minutes? Assume Ni metal
is plated out.
143.
Calculate the cell emf for the following reaction at 25C:
2Ag+(0.010 M) + H2(1 atm) → 2Ag(s) + 2H+(pH = 6.0)
Chapter 18 – Electrochemistry
144. A standard hydrogen electrode is immersed in an acetic acid solution. This electrode is
connected by an external circuit to an iron nail dipping into 0.10 M FeCl2. If Ecell is found to
be 0.24 V, what is the pH of the acetic acid solution?
145.
Consider the reaction Fe + Sn2+(1 10–3 M) → Fe2+(1.0 M) + Sn. Calculate the voltage theoretically generated by the cell.
Chapter 18 – Electrochemistry
146. How many moles of silver metal are produced in 1.2 hours by the electrolysis of
AgNO3(aq) using a current of 6.0 A?
147. How many grams of copper are deposited on the cathode of an electrolytic cell if an
electric current of 2.00 A is passed through a solution of CuSO4 for a period of 19.0 min?
Chapter 18 – Electrochemistry
148. An electroplating solution is made up of nickel(II) sulfate. How much time would it take
to deposit 0.500 g of metallic nickel on a custom car part using a current of 3.00 A?
149.
Many different ways have been proposed to make batteries. One cell is set up with copper and lead electrodes in contact with
CuSO4(aq) and Pb(NO3)2 (aq), respectively. If the Pb2+ and Cu2+ concentrations are each 1.0 M, what is the overall cell
potential?
Chapter 18 – Electrochemistry
150. Select True or False: A battery is constructed by placing copper and lead electrodes in
contact with 1.0 molar CuSO4(aq) and Pb(NO3)2 (aq) solutions, respectively. If sulfuric acid is
then added to the Pb(NO3)2 solution, thereby forming a precipitate of PbSO4, the cell potential
will decrease.
151. You wish to electroplate a metal utensil with a surface area of 736 cm2 with gold to give
an average thickness of 0.025 mm over the entire surface. Starting with a solution of excess
Au3+ and applying a constant current of 14 A, how long will it take to electroplate the utensil?
The density of gold is 19.3 g/cm3.
Chapter 18 – Electrochemistry
152. Select True or False: In an electrolytic cell, electrical energy is used to cause a chemical
reaction to occur that would otherwise be nonspontaneous.
153. Select True or False: When an aqueous solution of NaCl is electrolyzed, Na(l) is
produced at the cathode, and Cl2(g) is evolved at the anode.
154.
Select True or False: The electrochemical cell that utilizes the reaction Zn + Cu2+ (1 M) → Zn2+ (1 M) + Cu will have a lower
cell emf when the concentrations of Zn2+ and Cu2+ ions are decreased to 0.1 M.