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Exam 19: Electrochemistry: the Quest for Clean Energy

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Question 21

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If in using a lead-acid battery to start a car, 1.00 g of Pb is consumed on the anode, how long will it take to recharge the battery, using a current of 0.500 amperes, and turn the PbSO₄ that was produced back into Pb?

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Question 22

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Consider the following standard reduction potentials. $\begin{array} { | l | c | } \hline { \text { Reduction Half-Reaction } } & \mathbf { E } ^ { 0 } \text { (volts) } \\\hline \mathrm { Cr } ^ { 3 + } ( a q ) + 3 \mathrm { e } ^ { - } \longrightarrow \mathrm { Cr } ( s ) & - 0.74 \\\hline \mathrm { Cd } ^ { 2 + } ( a q ) + 2 \mathrm { e } ^ { - } \longrightarrow \mathrm { Cd } ( s ) & - 0.40 \\\hline \mathrm { Ni } ^ { 2 + } ( a q ) + 2 \mathrm { e } ^ { - } \longrightarrow \mathrm { Ni } ( s ) & - 0.23 \\\hline\end{array}$ Which reaction A-D will proceed spontaneously as written from left to right?

A) 2Cr³⁺(aq) + 3Cd(s) $\longrightarrow$ 2Cr(s) + 3Cd²⁺(aq)
B) 2Cr³⁺(aq) + 3Ni(s) $\longrightarrow$ 2Cr(s) + 3Ni²⁺(aq)
C) Cd²⁺(aq) + Ni(s) $\longrightarrow$ Cd(s) + Ni²⁺(aq)
D) Cd(s) + Ni²⁺(aq) $\longrightarrow$ Cd²⁺(aq) + Ni(s)
E) None of these will proceed spontaneously.

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Question 23

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When aluminum metal is obtained from aluminum oxide (Al₂O₃) , ________ moles of electrons must be transferred for each mole of aluminum oxide processed.

A voltaic cell is constructed based on the oxidation of zinc metal and the reduction of silver cations. Solutions of silver nitrate and zinc nitrate also were used. Locate the silver nitrate on the diagram.

Which statement about a voltaic cell is not correct?

Which statement about corrosion is not correct?

Consider the following standard reduction potentials. $\begin{array} { | l | c | } \hline { \text { Reduction Half-Reaction } } & \mathbf { E } ^ { 0 } \text { (volts) } \\\hline \mathrm { Mg } ^ { 2 + } ( a q ) + 2 \mathrm { e } ^ { - } \longrightarrow \mathrm { Mg } ( s ) & - 2.38 \\\hline \mathrm { Zn } ^ { 2 + } ( a q ) + 2 \mathrm { e } ^ { - } \longrightarrow \mathrm { Zn } ( s ) & - 0.76 \\\hline \mathrm { Cu } ^ { 2 + } ( a q ) + \mathrm { e } ^ { - } \longrightarrow \mathrm { Cu } ^ { + } ( a q ) & 0.16 \\\hline\end{array}$ The Mg/Mg²⁺ half-reaction can be paired with the other two to produce voltaic cells because ________

The oxidation of hydrogen by oxygen is one of the most-used reactions in fuel-cell technology. The overall reaction, which is given below, has a $\Delta$ G° value of -237 kJ/mol. What is the standard cell potential for this fuel cell? H₂(g) + $\frac { 1 } { 2 }$ O₂(g) $\rightarrow$ H₂O(l)

What is the change in free energy for a 1.50-V alkaline battery in which 2 moles of electrons are transferred from the anode to the cathode?

Use the table of standard reduction potentials below to identify the metal or metal ion that is the strongest oxidizing agent. Standard Reduction Potentials (volts) in Aqueous Solution $\begin{array} { l l } \mathrm { Pb } ^ { 4 + } + 2 \mathrm { e } ^ { - } \rightarrow \mathrm { Pb } ^ { 2 + } & + 1.80 \\\mathrm { Au } ^ { 3 + } + 3 \mathrm { e } ^ { - } \rightarrow \mathrm { Au } & + 1.50 \\\mathrm { Fe } ^ { 3 + } + 3 \mathrm { e } ^ { - } \rightarrow \mathrm { Fe } & + 0.771 \\\mathrm { I } _ { 2 } + 2 \mathrm { e } ^ { - } \rightarrow 2 \mathrm { I } ^ { - } & + 0.535 \\\mathrm {~Pb} ^ { 2 + } + 2 \mathrm { e } ^ { - } \rightarrow \mathrm { Pb } & - 0.124 \\\mathrm { Al } ^ { 3 + } + 3 \mathrm { e } ^ { - } \rightarrow \mathrm { Al } & - 1.66 \\\mathrm { Mg } ^ { 2 + } + 2 \mathrm { e } ^ { - } \rightarrow \mathrm { Mg } & - 2.37 \\\mathrm {~K} ^ { + } + \mathrm { e } ^ { - } \rightarrow \mathrm { K } & - 2.93\end{array}$

Chromium often is electroplated on other metals and even plastics to produce a shiny metallic appearance. How many grams of chromium would plate out from a solution of Cr(NO₃)₃ when 10 amps of current are passed through the electrolytic cell for 5.36 hours?

Neuron cells generate electrical signals by concentration gradients across membranes. Assuming a potassium ion concentration of 0.003 M inside the cell, and a concentration of 0.135 M outside the cell, what is the electrical potential across the cell membrane? Body temperature is 310 K. The sign identifies the change in the electrical potential across the membrane and which way the ions flow.

The energy supplied by a battery can be determined by ________

Consider the voltaic cell based on the following reaction: Ma(s) + Mb⁺(aq) $\rightarrow$ Ma⁺(aq) + Mb(s) Two students are assigned to measure the standard cell potential. Yvonne claims that both solutions of ions have to be at exactly 1.00 M concentration, but Zelda is sure that the measurement will be the same if the concentrations of the two solutions are equal, but not necessarily 1.00 M. What do you think? (The temperature is controlled at 25°C, so that's not an issue.)

The unit of current, ampere (A) , is defined as ________

A NiMH battery uses ________ as the reducing agent.

How do fuel cells differ from traditional electrochemical cells (batteries) ?

The following reaction occurs in a new battery called the super iron battery. In this reaction, ________ is oxidized. 2K₂FeO₄(aq) + 3Zn(s) $\longrightarrow$ Fe₂O₃(s) + ZnO(s) + 2K₂ZnO₂(aq)

The spontaneous redox reaction in a voltaic cell has ________

Which statement regarding voltaic cells is not correct?