Electrochemistry

The cell potential of a galvanic cell is always:

What is the standard potential ($E^{\circ}$) of the Standard Hydrogen Electrode (SHE) at all temperatures?

Which material is commonly used as an inert electrode in electrochemical cells?

What happens to the concentration of $Zn^{2+}$ ions in the anode compartment of a $Zn-Cu$ galvanic cell as it operates?

In the cell $Pt(s) | H_2(g, 1 bar) | H^+(aq, 1 M) || Ag^+(aq, 1 M) | Ag(s)$, what is the cathode reaction?

Which of the following electrolytes would be most suitable for use in a salt bridge?

For a spontaneous reaction in an electrochemical cell, which of the following conditions must be met?

A sensor utilizes the cell $Pt | H_2 (1\,bar) | HCl (pH = x) || AgCl(s) | Ag | Pt$. The measured $E_{cell}$ is $0.495\,V$ at $298\,K$. Given $E^0_{AgCl/Ag, Cl^-} = 0.222\,V$ and the concentration of $Cl^-$ is $0.1\,M$, calculate the unknown pH ($x$). (Take $0.059$ for Nernst factor)

An electrochemist measures the equilibrium constant ($K_c$) for the reaction $Zn(s) + Cu^{2+}(aq) \rightleftharpoons Zn^{2+}(aq) + Cu(s)$ at $298\,K$. If the $E^0_{cell}$ is $1.1\,V$, which expression correctly calculates the value of $log\,K_c$?

A hydrogen-oxygen fuel cell is used in a spacecraft. The cell operates on the reaction $2H_2(g) + O_2(g) \rightarrow 2H_2O(l)$. If the standard Gibbs energy of formation of $H_2O(l)$ is $-237.2\,kJ/mol$, calculate the standard EMF ($E^0$) of the fuel cell.

The EMF of a cell is the potential difference between two electrodes when:

Standard Electrode Potential is measured at what concentration of the electrolyte?

What happens to the concentration of $Cu^{2+}$ ions in a Daniell cell as it operates?

If $E^o_{cell}$ is positive, the cell reaction is:

What is the potential of a Standard Hydrogen Electrode (SHE) at all temperatures according to convention?

In a galvanic cell using the reaction $Cu(s) + 2Ag^+(aq) \rightarrow Cu^{2+}(aq) + 2Ag(s)$, what happens if the concentration of $Ag^+$ is doubled?

The equilibrium constant $K$ for a cell reaction is related to $E^o_{cell}$ by which expression at 298 K?

A galvanic cell consists of a Gold electrode ($E^o_{Au^{3+}/Au} = +1.50\, V$) and a Thallium electrode ($E^o_{Tl^{+}/Tl} = -0.34\, V$). What is the maximum work (electrical) that can be obtained from the reaction of $1\, mole$ of Gold ions under standard conditions?

A student constructs a cell using Aluminium ($E^o = -1.66\, V$) and Tin ($E^o = -0.14\, V$). If the cell is discharging and the concentration of $Al^{3+}$ increases from $0.01\, M$ to $0.1\, M$ while $Sn^{2+}$ is maintained at $1.0\, M$, by how much does the cell potential change?

An experimental fuel cell uses the reaction $2H_2(g) + O_2(g) \rightarrow 2H_2O(l)$. If the standard Gibbs free energy of formation for $H_2O(l)$ is $-237.2\, kJ/mol$, calculate the standard EMF of this fuel cell.

Which of the following correctly identifies the term '$\ln Q$' in the natural log form of the Nernst equation?

What is the standard potential of a half-cell where the concentration of ions is $1\text{ M}$ and the temperature is $298\text{ K}$?

In the context of the Nernst equation, what happens to the cell potential as the battery is used up?

If $E_{cell}$ for a specific reaction is negative, the reaction in the forward direction is:

Calculate the electrode potential of a fluorine electrode ($F_2/F^{-}$) at $298\text{ K}$ where $P_{F2} = 2\text{ atm}$ and $[F^{-}] = 0.1\text{ M}$. (Given: $E^\circ = 2.87\text{ V}$)

If the $E^\circ_{cell}$ for a reaction is negative, then:

For the cell $Pt|H_2(p_1)|H^{+}(1\text{ M})||H^{+}(1\text{ M})|H_2(p_2)|Pt$, the cell potential at $298\text{ K}$ is given by:

Calculate $E_{cell}$ for $Al | Al^{3+}(0.01\text{ M}) || Sn^{2+}(0.01\text{ M}) | Sn$ at $298\text{ K}$. (Given: $E^\circ_{Al^{3+}/Al} = -1.66\text{ V}, E^\circ_{Sn^{2+}/Sn} = -0.14\text{ V}$)

A cell reaction reaches equilibrium. Which of the following is true according to the Nernst equation?

Given the half-reaction: $Cr_2O_7^{2-} + 14H^+ + 6e^- \rightarrow 2Cr^{3+} + 7H_2O$. If the concentration of $Cr_2O_7^{2-}$ is $0.1\text{ M}$, $Cr^{3+}$ is $0.2\text{ M}$, and $pH = 2$, calculate the reduction potential. ($E^\circ = 1.33\text{ V}$)

Which type of conductance decreases with the increase in concentration of the electrolyte?

What is the unit of $A$ in the equation $\Lambda_m = \Lambda_m^0 - A\sqrt{C}$?

Molar conductivity of a weak electrolyte ___________ sharply with dilution.

If the specific conductance of a solution is $0.02 S cm^{-1}$ and the resistance is $50 \Omega$, what is the cell constant?

Which of the following has the unit $S\ cm^{-1}$?

The value of $\Lambda_m^0$ for $NH_4Cl$, $NaOH$ and $NaCl$ are $129.8$, $248.1$ and $126.4\ S\ cm^2\ mol^{-1}$ respectively. Calculate the $\Lambda_m^0$ for $NH_4OH$.

For a strong electrolyte, if the concentration is increased by 4 times, the term $\sqrt{c}$ in the Debye-Huckel-Onsager equation will:

Which of the following would show the highest molar conductivity at infinite dilution in water at $25^\circ C$?

The ratio of molar conductivity to equivalent conductivity for a solution of $Al_2(SO_4)_3$ is:

For a sparingly soluble salt $MX$, the specific conductance of its saturated solution is $1.8 \times 10^{-5}\ S\ cm^{-1}$ and that of water is $2.0 \times 10^{-6}\ S\ cm^{-1}$. If $\Lambda_m^\circ(MX) = 160\ S\ cm^2\ mol^{-1}$, the solubility of $MX$ is:

Kohlrausch's law helps in calculating the solubility of a sparingly soluble salt ($S$) using the relation:

For which electrolyte does $\Lambda_m$ increase very sharply at very low concentrations?

Which of the following represents the correct application of Kohlrausch's law for $Mg(NO_3)_2$?

The limiting molar conductivity of $AgNO_3$ is the sum of $\lambda^o$ for:

If the molar conductivity of $CuSO_4$ at infinite dilution is $X$, and the limiting ionic conductivity of $SO_4^{2-}$ is $Y$, what is the limiting ionic conductivity of $Cu^{2+}$?

Kohlrausch's Law is valid for:

If the limiting molar conductivity of $CH_3COOH$ is $390.5 \text{ S cm}^2 \text{ mol}^{-1}$ and the molar conductivity of a $0.01 \text{ M}$ solution is $39.05 \text{ S cm}^2 \text{ mol}^{-1}$, what is the value of $pKa$?

Based on the provided diagram of molar conductivity vs. square root of concentration, identify which curve represents a weak electrolyte and how its limiting value is obtained.

A $0.01 \text{ M}$ weak acid solution has $\Lambda_{m} = 20 \text{ S cm}^{2} \text{ mol}^{-1}$. If $K_{a} = 10^{-5}$, what is the $\Lambda_{m}^{\infty}$ for this acid?

At infinite dilution, the ionic conductivities of $NH_{4}^{+}$ and $SO_{4}^{2-}$ are $73.5$ and $160 \text{ S cm}^{2} \text{ mol}^{-1}$. Find the $\Lambda_{m}^{\infty}$ for $(NH_{4})_{2}SO_{4}$.

During the electrolysis of $CuSO_4$ using platinum electrodes, the blue color of the solution eventually:

One Faraday is equal to the charge of:

The process of loss of electrons by an ion at the anode is called:

Which of the following is NOT a characteristic of a strong electrolyte?

The weight of silver (eq. wt. $= 108$) displaced by that quantity of electricity which displaces $5600\ mL$ of $O_2$ at STP is:

What is the ratio of the volume of $H_2$ to $O_2$ produced during the electrolysis of water?

Which of the following is the mass of one mole of electrons?

What is the quantity of electricity (in Coulombs) required to liberate $112\ mL$ of $H_2$ at STP during the electrolysis of an acidulated water?

An electric current is passed through a solution of $ZnSO_4$. The mass of zinc (atomic mass 65.4) deposited by $9650\ C$ is:

Three Faradays of electricity are passed through molten $Al_2O_3$, aqueous $CuSO_4$, and molten $NaCl$. The amount of $Al$, $Cu$, and $Na$ deposited are in the ratio:

Why is a dry cell not truly 'dry'?

In a dry cell, the electrolyte is a moist paste of:

Which of the following is a primary cell?

What is the approximate voltage provided by a single cell of a lead-acid battery?

The specific gravity of $H_2SO_4$ in a fully charged lead accumulator is approximately:

What happens to the $PbSO_4$ formed during discharge of a lead accumulator?

Which of the following is a disadvantage of the lead-acid battery?

Consider the thermodynamics of a dry cell. Even when not in use, these cells have a limited shelf life. Which side reaction involving the zinc anode and the $NH_4Cl$ electrolyte is the primary cause of this shelf-life limitation?

If a lead accumulator is left in a discharged state for a long duration, 'sulfation' occurs, making it difficult to recharge. What is the chemical nature of this 'sulfation'?

In the context of the Leclanché dry cell, the build-up of ammonia gas would normally cause the internal pressure to rise and the cell to burst. How is this risk chemically managed within the cell's design?

Which of the following fuels can be used in a fuel cell other than hydrogen?

In a fuel cell, the electrodes are made porous to:

Which of these is a major advantage of using fuel cells in spacecraft like the Apollo mission?

The overall reaction in a $H_2-O_2$ fuel cell is the same as the combustion of hydrogen. What is it?

How does the efficiency $(\eta)$ of a fuel cell relate to the thermodynamic properties of the cell reaction?

What is the primary product of the reaction at the anode of a methanol-oxygen fuel cell in acidic medium?

Which of the following correctly describes the movement of ions in a $H_2-O_2$ fuel cell using aqueous $KOH$ as the electrolyte?

A Molten Carbonate Fuel Cell (MCFC) uses a mixture of $Li_2CO_3$ and $K_2CO_3$ as the electrolyte. The net cathode reaction is $0.5O_2 + CO_2 + 2e^- \rightarrow CO_3^{2-}$. If the cell is integrated into a carbon capture system where $44$ g of $CO_2$ is recycled through the cathode every minute, what is the theoretical current produced by the cell?

A bio-fuel cell utilizes glucose oxidation at the anode: $C_6H_{12}O_6 + 6H_2O \rightarrow 6CO_2 + 24H^+ + 24e^-$. If a medical implant requires a continuous current of $1$ mA and the fuel cell has a glucose reservoir of $180$ mg, how long can the implant operate before the fuel is exhausted? ($M_{glucose} = 180$ $g/mol$)

In the Apollo space missions, the $H_2-O_2$ fuel cell provided both electricity and drinking water. If the thermodynamic efficiency $\eta = \Delta G / \Delta H$ of the cell is $83\%$ and the enthalpy of combustion of hydrogen $\Delta H$ is $-285.8$ $kJ/mol$, calculate the maximum work ($w_{max}$) obtainable from the consumption of $1$ kg of hydrogen gas.

In cathodic protection, the iron object is made the ___________ of the circuit.

The term 'Tarnishing' is most commonly associated with which metal?

Which of the following is used in 'Phosphating' to protect iron?

Which of the following is a result of corrosion?

Which of the following best describes 'pitting corrosion'?

If an iron object is placed in a desiccator containing anhydrous calcium chloride, why does it not rust?

Why is 'red lead' ($Pb_3O_4$) used as a primer paint on iron structures?

Why does aluminum appear to be more 'noble' than iron in everyday use, despite having a much more negative standard reduction potential ($E^o_{Al^{3+}/Al} = -1.66 V$, $E^o_{Fe^{2+}/Fe} = -0.44 V$)?

Which of the following factors does NOT determine the 'Throwing Power' of a cathodic protection system?

The term 'Stray Current Corrosion' refers to corrosion caused by: