The Nernst Equation

A concentration cell consists of two Sn/ Sn2+ half-cells. The cell has a potential of 0.10 V at 25°C. What is the ratio of the Sn2+ concentrations in the two half-cells?

A Cu/Cu2+ concentration cell has a voltage of 0.22 V at 25°C. The concentration of Cu2+ in one of the half-cells is 1.5 X 10–3 M. What is the concentration of Cu 2+ in the other half-cell? (Assume the concentration in the unknown cell to be the lower of the two concentrations.)

An electrochemical cell is constructed using the half-reactions given in the table below. A. What is the overall chemical equation for the  spontaneous redox reaction that would occur under standard conditions?     B. Which half-reaction is acting as the anode under standard conditions?    C. What is E° for this reaction?       D. What is n for this reaction? __________   E. Write the expression for Q for the reaction.   F. The cell was constructed with [Ni 2+] = 0.139 M and an unknown concentration of Cu + (aq). A potential of 0.604 V was measured for the cell under those conditions. What is the concentration of Cu+ (aq)?        

Calculate the cell potential for the following reaction that takes place in an electrochemical cell at 25 degrees C. Sn(s) │ Sn2+ (aq, 0.022M) ║ Ag+ (aq, 2.7M) │Ag(s)   Sn2++ 2e–→ Sn(s)  E◦cell = – 0.14   Ag+ + 1e– → Ag(s) E◦cell = 0.8 A. -0.83 V B. +1.31 V C. -0.66 V D. +1.01 V E. +0.01 V

The cell potential of this electrochemical cell depends on the pH of the solution in the anode half-cell. Pt(s) | H2(g, 1 atm) | H+(aq,? M) || Cu2+(aq, 1.0M) | Cu(s) What is the pH of the solution if E cell is 355 mV?

The cell potential of this electrochemical cell depends on the gold concentration in the cathode half-cell. Pt(s) | H2(g, 1.0 atm) | H+(aq, 1.0 M) || Au3+(aq, ? M) | Au(s) What is the concentration of Au3+ in the solution if Ecell is 1.22 V?

A battery relies on the oxidation of magnesium and the reduction of Cu 2+. The initial concentrations of Mg2+ and Cu2+ are 1.0 x 10–4 M and 1.5 M, respectively, in 1.0-liter half-cells. a. What is the initial voltage of the battery?

An MnO2(s)/Mn2+(aq) electrode in which the pH is 10.24 is prepared. Find the [Mn 2+] necessary to lower the potential of the half-cell to 0.00 V (at 25°C).

To what pH should you adjust a standard hydrogen electrode to get an electrode potential of –0.122 V? (Assume that the partial pressure of hydrogen gas remains at 1 atm.)

Consider the following electrochemical cell for the question: Pt / KBr(aq, 0.01 M), Br2(l) // FeBr2(aq, 1.0M) / Fe What is the name of the ionic compound in the anode compartment? (a) iron(II) bromide (b) potassium bromide (c) sodium bromine (d) iron bromine (e) potassium(I) bromate (ab) iron(IV) bromate     What is E°cell? (that is, what is Ecell if all reagents were present under standard conditions?) a) 0.64 V b) -1.54 V  c) -0.64 V d) 1.54 V e) -0.32 V  ab) 0.32 V

An electrochemical cell has the following half cell reactions: Cu2+(aq) +2e- → Cu(s)          E°1/2 = +0.34 Zn2+(aq) + 2e- → Zn(s)          E°1/2 = -0.76 If the cell operates with the Cu electrode as the cathode and the Zn as the anode, What is the cell potential when the [Cu2+] = 0.001M and the [Zn2+] = 0.1M? A) 1.159V B) -1.159 V C) +0.479 V D) -0.479 V E) +1.041 V

Consider the redox reaction: PbO2(s)  +  Ba(s)  +  4H+ (aq)  →  Pb+2 (aq)  +  Ba +2 (aq) + 2H2O(l)  At standard conditions ε° = 4.36 V (highly spontaneous). Suppose the voltage ε, is measured for the above reaction when the [H+] concentration is [H+] = 10 -7 M instead of [H+] = 1M. How does ε compare to ε° (circle one): ε > ε°        ε < ε°         ε = ε°        Can't be determined

For the reaction:                                     Sn    4+(aq)+  2 Cu+(aq)  →   2 Cu2+(aq)+  Sn2+(aq) If the concentrations of the reactants are: [Sn2+] is 0.66 M, [Cu+] = [0.03M], [Sn4+] = 0. 01M, [Cu2+] = [0.5M] what is the cell potential?                                                                                         E         o1/2 cell                                     2e–  +  Sn4+(aq) → Sn2+(aq)             +0.13                                     e–  +  Cu2+(aq)  →  Cu1+(aq)            +0.15                         A)        –0.146 V             B)        –0.11V             C)        +0.28 V             D)        +0.272 V             E)         –0. 299 V

The standard emf for the cell with the following overall cell reaction is +0.48 V:  Zn (s) + Ni2+(aq) → Zn2+ (aq) + Ni (s)   What is the emf generated by a similar cell with [Ni 2+]=2.50 M and [Zn2+]=0.100 M? a) 0.40 V b) 0.50 V c) 0.52 V d) 0.56 V e) 0.44 V  

Consider a standard voltaic cell based on the reaction: 2 H+ (aq) + Sn (s) → Sn2+ (aq) + H2 (g) Which of the following actions would change the emf of the cell? a) Increasing the pH at the cathode b) Lowering the pH at the cathode c) Increasing [Sn2+] at the anode d) Increasing the hydrogen gas pressure at the cathode e) All of the above changes will alter the cell potential  

A voltaic cell employs the redox reaction: 2Fe3+(aq) + 3Mg(s) → 2Fe(s) + 3Mg2+(aq) Calculate the cell potential at 25°C under each set of conditions. a. standard cond itions

A voltaic cell employs the redox reaction: 2Fe3+(aq) + 3Mg(s) → 2Fe(s) + 3Mg2+(aq). Calculate the cell potential at 25°C under each set of conditions b. [Fe3+] = 1.0 X 10–3 M; [Mg2+] = 2.50 M

A voltaic cell employs the redox reaction: 2Fe3+(aq) + 3Mg(s) → 2Fe(s) + 3Mg2+(aq). Calculate the cell potential at 25°C under each set of conditions c. [Fe3+] = 2.00 M; [Mg2+] = 1.5 x 10–3 M

A voltaic cell consists of a Pb/ Pb2+ half-cell and a Cu/Cu2+ half-cell at 25°C. The initial concentrations of Pb2+ and Cu2+ are 0.0500 M and 1.50 M, respectively. b. What is the cell potential when the concentration of Cu 2+ has fallen to 0.200 M?

Consider this reaction.  4 e – + 4 H+ (aq) + O2 (g) ⇌ 2 H2O (l)     E° = 1.23 V Which statement is true if the hydrogen ion concentration is initially at 1.0 M and the initial pressure of oxygen gas is 1.0 atmosphere?  

Concentration cell based on the Ni2+-Ni cell reaction. (a) Concentrations of Ni2+(aq) in the two half-cells are unequal, and the cell generates an electrical current and a voltage. (b) The cell operates until [Ni2+] is the same in the two half-cells, at which point the cell has reached equilibrium and the emf goes to zero.Which electrode, if any, loses mass as the reaction proceeds?

A voltaic cell is constructed froman Ni2 + (aq) - Ni(s) half-cell andan Ag+ (aq) - Ag(s) half-cell.The initial concentration of Ni2 + (aq) in the Ni2 + - Ni half-cell is [Ni2 + ] = 1.50×10−2 M . The initial cell voltage is +1.13 V .Will the concentration of Ni2 + (aq) increase or decrease as the cell operates?

A voltaic cell is constructed froman Ni2 + (aq) - Ni(s) half-cell andan Ag+ (aq) - Ag(s) half-cell.The initial concentration of Ni2 + (aq) in the Ni2 + - Ni half-cell is [Ni2 + ] = 1.50×10−2 M . The initial cell voltage is +1.13 V .What is the initial concentration of Ag+ (aq) in the Ag+ - Ag half-cell?

A voltaic cell is constructed that uses the following half-cell reactions: l Cu+ (aq) + e-  →  Cu(s)I2 (s) + 2e-  →  2I- (aq) .The cell is operated at 298 K with [Cu+ ] = 0.26 M and [I- ] = 3.6 M .Determine E for the cell at these concentrations.

A voltaic cell is constructed that uses the following half-cell reactions: l Cu+ (aq) + e-  →  Cu(s)I2 (s) + 2e-  →  2I- (aq) .The cell is operated at 298 K with [Cu+ ] = 0.26 M and [I- ] = 3.6 M .If [Cu+ ] was equal to 0.16 M , at what concentration of I- would the cell have zero potential?

In a galvanic cell the cathode is an Ag+ (1.00 M)/Ag(s) half-cell. The anode is a standard hydrogen electrode immersed in a buffer solution containing 0.10 M benzoic acid (C6 H5 COOH) and 0.050 M sodium benzoate (C6 H5 COO- Na+ ). The measured cell voltage is 1.030 V.What is the pKa of benzoic acid?

To what pH should you adjust a standard hydrogen electrode to get an electrode potential of -0.122 V ? (Assume that the partial pressure of hydrogen gas remains at 1 atm.)

Consider the following voltaic cell. What is the change in the cell voltage when the ion concentrations in the cathode half-cell are increased by a factor of 10?

Suppose a hydrogen-oxygen fuel-cell generator was used to produce electricity for a house. Use the balanced redox reactions and the standard cell potential to predict the volume of hydrogen gas (at STP) required each month to generate the electricity needed for a typical house. Assume the home uses 1400 kWh of electricity per month.

Consider the following voltaic cell. What is the change in the cell voltage when the ion concentrations in the anode half-cell are increased by a factor of 10?

How does Ecell depend on the concentrations of the reactants and products in the redox reaction occurring in the cell? What effect does increasing the concentration of a reactant have on Ecell? Increasing the concentration of a product?

What is the effect on the emf of the cell shown in Figure 20.9 in the textbook, which has the overall reaction Zn(s) + 2H+(aq)  →  Zn2+(aq) + H2(g), for each of the following changes?The pressure of the H2 gas is increased in the cathode compartment.

What is the effect on the emf of the cell shown in Figure 20.9 in the textbook, which has the overall reaction Zn(s) + 2H+(aq)  →  Zn2+(aq) + H2(g), for each of the following changes?Zinc nitrate is added to the anode compartment.

What is the effect on the emf of the cell shown in Figure 20.9 in the textbook, which has the overall reaction Zn(s) + 2H+(aq)  →  Zn2+(aq) + H2(g), for each of the following changes?Sodium hydroxide is added to the cathode compartment, decreasing left[{ m H^+} ight].

What is the effect on the emf of the cell shown in Figure 20.9 in the textbook, which has the overall reaction Zn(s) + 2H+(aq)  →  Zn2+(aq) + H2(g), for each of the following changes?The surface area of the anode is doubled.

A voltaic cell is constructed that uses the following reaction and operates at 298 K: Zn(s) + Ni2 + (aq)  →  Zn2 + (aq) + Ni(s).What is the emf of this cell when [Ni2 + ] = 3.10 M and [Zn2 + ] = 0.160 M ?

A voltaic cell is constructed that uses the following reaction and operates at 298 K: Zn(s) + Ni2 + (aq)  →  Zn2 + (aq) + Ni(s).What is the emf of the cell when [Ni2 + ] = 0.210 M and [Zn2 + ] = 0.900 M ?

A voltaic cell utilizes the following reaction: 4Fe2 + (aq) + O2 (g) + 4H+ (aq)  →  4Fe3 + (aq) + 2H2 O(l).What is the emf of this cell when [Fe2 + ] = 1.6 M , [Fe3 + ] = 1.6×10−2 M , PO2 = 0.51 atm and the pH of the solution in the cathode compartment is 3.6?

A voltaic cell is constructed with two Zn2 + - Zn electrodes. The two cell compartments have [Zn2 + ] = 1.8 M and [Zn2 + ] = 1.60×10−2 M , respectively.What is the standard emf of the cell?

A voltaic cell is constructed with two Zn2 + - Zn electrodes. The two cell compartments have [Zn2 + ] = 1.8 M and [Zn2 + ] = 1.60×10−2 M , respectively.What is the cell emf for the concentrations given?

A voltaic cell is constructed with two Zn2 + - Zn electrodes. The two cell compartments have [Zn2 + ] = 1.8 M and [Zn2 + ] = 1.60×10−2 M , respectively.For the anode compartment, predict whether [Zn2 + ] will increase, decrease, or stay the same as the cell operates.

A voltaic cell is constructed with two Zn2 + - Zn electrodes. The two cell compartments have [Zn2 + ] = 1.8 M and [Zn2 + ] = 1.60×10−2 M , respectively.For the cathode compartment, predict whether [Zn2 + ] will increase, decrease, or stay the same as the cell operates.

A voltaic cell is constructed with two silver-silver chloride electrodes, each of which is based on the following half-reaction: AgCl(s) + e-  →  Ag(s) + Cl- (aq).The two cell compartments have [Cl- ] = 1.51×10−2 M and [Cl- ] = 2.60 M , respectively.What is the standard emf of the cell?

A voltaic cell is constructed with two silver-silver chloride electrodes, each of which is based on the following half-reaction: AgCl(s) + e-  →  Ag(s) + Cl- (aq).The two cell compartments have [Cl- ] = 1.51×10−2 M and [Cl- ] = 2.60 M , respectively.What is the cell emf for the concentrations given?

A voltaic cell is constructed with two silver-silver chloride electrodes, each of which is based on the following half-reaction: AgCl(s) + e-  →  Ag(s) + Cl- (aq).The two cell compartments have [Cl- ] = 1.51×10−2 M and [Cl- ] = 2.60 M , respectively.For the anode compartment, predict whether [Cl- ] will increase, decrease, or stay the same as the cell operates.

A voltaic cell utilizes the following reaction and operates at 298 K: 3Ce4 + (aq) + Cr(s)  →  3Ce3 + (aq) + Cr3 + (aq).What is the emf of this cell when [Ce4 + ] = 2.6 M , [Ce3 + ] = 0.16 M , and [Cr3 + ] = 1.6×10−2 M ?

A voltaic cell utilizes the following reaction and operates at 298 K: 3Ce4 + (aq) + Cr(s)  →  3Ce3 + (aq) + Cr3 + (aq).What is the emf of the cell when [Ce4 + ] = 1.3×10−2 M ,[Ce3 + ] = 2.3 M , and [Cr3 + ] = 1.6 M ?

A voltaic cell is constructed as follows: Ag(s) | Ag+(satdAg 2CrO4) || Ag+( 0.110 M ) | Ag(s) What is the value of Ecell? For Ag2CrO4, Ksp = 1.1 × 10−12.

Complete this table relating the values of Ecell and ΔG to the Q/K ratio. 

If there is an electrochemical cell and Q = 0.0010 and K = 0.10, which is true about Ecell and E°cell?a. Ecell is positive and E°cell is negativeb. Ecell is negative and E°cell is positivec. Both Ecell and E°cell are positived. Both Ecell and E°cell are negative

If there is an electrochemical cell and Q=0.0010 and K=0.10, which is true about Ecell and Eθcell?a. Ecell is positive and Eθcell is negativeb. Ecell is negative and Eθcell is positivec. Both Ecell and Eθcell are positived. Both Ecell and Eθcell are negative

Calculate the equilibrium constant for each of the reactions at 25°C. Express your answer using two significant figures. a. 2Fe3+(aq) + 3Sn(s) → 2Fe(s) + 3Sn 2+(aq) b. O2(g) + 2H2O(l) + 2Cu(s) → 4OH−(aq) + 2Cu2+(aq) c. 2Cr3+(aq) + 3Ni(s) → 2Cr(s) + 3Ni 2+(aq) 

Consider a galvanic cell based on the following half-reactions:f. If this cell is set up at 25°C with [Fe 2+] = 2.00 x 10 -4 M and [La3+] = 3.00 x 10 -3 M, what is the expected cell potential?

A voltaic cell utilizes the following reaction:2Fe3+(aq) + H2(g)  →  2Fe2+(aq) + 2H+(aq).What is the emf for this cell when [Fe3+ ]  = 3.60 M, PH2  = 0.96 atm, [Fe2+ ] = 0.0012 M, and the pH in both compartments is 4.00?

A voltaic cell consists of a standard reference half-cell and a Cu/Cu 2+ half-cell. Calculate [Cu2+] when Ecell is 0.22 V.

A chemist designs an ion-specific probe for measuring [Ag +] in an NaCl solution saturated with AgCl. One half-cell has an Ag wire electrode immersed in the unknown AgCl-saturated NaCl solution. It is connected through a salt bridge to the other half-cell, which has a calomel reference electrode [a platinum wire immersed in a paste of mercury and calomel (Hg2Cl2)] in a saturated KCl solution. The measured Ecell is 0.060 V.(a) Given the following standard half-reactions, calculate [Ag +].Calomel: Hg2Cl2(s) + 2e− ⟶ 2Hg(l) + 2Cl−(aq)             E° = 0.24 VSilver: Ag+(aq) + e− ⟶ Ag(s)                                         E° = 0.80 V(Hint: Assume that [Cl−] is so high that it is essentially constant.)

A voltaic cell consists of an Mn/Mn2+ half-cell and a Pb/Pb2+ half-cell. Calculate [Pb2+] when [Mn2+] is 1.4 M and Ecell is 0.44 V.

A chemist designs an ion-specific probe for measuring [Ag +] in an NaCl solution saturated with AgCl. One half-cell has an Ag wire electrode immersed in the unknown AgCl-saturated NaCl solution. It is connected through a salt bridge to the other half-cell, which has a calomel reference electrode [a platinum wire immersed in a paste of mercury and calomel (Hg2Cl2)] in a saturated KCl solution. The measured Ecell is 0.060 V.(b) A mining engineer wants an ore sample analyzed with the Ag +-selective probe. After pretreating the ore sample, the chemist measures the cell voltage as 0.53 V. What is [Ag+]?

A voltaic cell with Ni/Ni 2+ and Co/Co2+ half-cells has the following initial concentrations: [Ni2+] = 0.80 M; [Co 2+] = 0.20 M.(a) What is the initial Ecell?

A voltaic cell with Ni/Ni 2+ and Co/Co2+ half-cells has the following initial concentrations: [Ni2+] = 0.80 M; [Co 2+] = 0.20 M.(b) What is [Ni2+] when Ecell reaches 0.03 V?

A voltaic cell with Ni/Ni 2+ and Co/Co2+ half-cells has the following initial concentrations: [Ni2+] = 0.80 M; [Co 2+] = 0.20 M.(c) What are the equilibrium concentrations of the ions?

Heart pacemakers are often powered by lithium-silver chromate "button" batteries. The overall cell reaction is:2Li(s) + Ag2CrO4(s)  →  Li2CrO4(s) + 2Ag(s)(b) Choose the two half-reactions from Appendix E that most closely approximate the reactions that occur in the battery. What standard emf would be generated by a voltaic cell based on these half-reactions? (c) The battery generates an emf of +3.5 V. How close is this value to the one calculated in part (b)? (d) Calculate the emf that would be generated at body temperature, 37 °C. How does this compare to the emf you calculated in part (b)?

A voltaic cell with Mn/Mn 2+ and Cd/Cd 2+ half-cells has the following initial concentrations: [Mn2+] = 0.090 M; [Cd 2+] = 0.060 M.(a) What is the initial Ecell?

Consider the following half-reactions:IrCl63- + 3e- → Ir + 6Cl -         ε° = 0.77 VPtCl42- + 2e- → Pt + 4Cl -       ε° = 0.73 VPdCl42- + 2e- →Pd + 4Cl -      ε° = 0.62 VA hydrochloric acid solution contains platinum, palladium, and iridium as chloro-complex ions. The solution is a constant 1.0 M in chloride ion and 0.020 M in each complex ion. Is it feasible to separate the three metals from this solution by electrolysis? (Assume that 99% of a metal must be plated out before another metal begins to plate out.)

A voltaic cell with Mn/Mn 2+ and Cd/Cd 2+ half-cells has the following initial concentrations: [Mn2+] = 0.090 M; [Cd 2+] = 0.060 M.(b) What is Ecell when [Cd 2+] reaches 0.050 M?

A voltaic cell with Mn/Mn 2+ and Cd/Cd 2+ half-cells has the following initial concentrations: [Mn2+] = 0.090 M; [Cd 2+] = 0.060 M.(c) What is [Mn2+] when Ecell reaches 0.055 V?

A voltaic cell with Mn/Mn 2+ and Cd/Cd 2+ half-cells has the following initial concentrations: [Mn2+] = 0.090 M; [Cd 2+] = 0.060 M.(d) What are the equilibrium concentrations of the ions?

A voltaic cell consists of two H2/H+ half-cells. Half-cell A has H2 at 0.95 atm bubbling into 0.10 M HCl. Half-cell B has H2 at 0.60 atm bubbling into 2.0 M HCl. Which half-cell houses the anode? What is the voltage of the cell?

A voltaic cell consists of two Sn/Sn 2+ half-cells, A and B. The electrolyte in A is 0.13 M Sn(NO3)2. The electrolyte in B is 0.87 M Sn(NO 3)2. Which half-cell houses the cathode? What is the voltage of the cell?

A voltaic cell employs the following redox reaction: Sn2+(aq) + Mn(s) → Sn(s) + Mn2+(aq)Calculate the cell potential at 25˚C under each of the following conditions: [Sn2+] = 1.51×10−2 M; [Mn2+] = 2.01 M

A voltaic cell employs the following redox reaction: Sn2+(aq) + Mn(s) → Sn(s) + Mn2+(aq)Calculate the cell potential at 25˚C under each of the following conditions: [Sn2+] = 2.01 M; [Mn2+] = 1.51×10−2 M

Consider a concentration cell similar to the one shown below, except that both electrodes are made of Ni and in the left-hand compartment [Ni2+] = 1.0 M. Calculate the cell potential at 25°C when the concentration of Ni2+ in the compartment on the right has each of the following values.b. 2.0 MFor each case, also identify the cathode, anode, and the direction in which electrons flow.

An electrochemical cell is based on the following two half-reactions:Ox: Pb(s) → Pb2+(aq, 0.21 M) + 2 e–Red: MnO4–(aq, 1.50 M) + 4 H+(aq, 2.1 M) + 3 e– → MnO2(s) + 2 H2O(l)Compute the cell potential at 25 ˚C.

Consider a concentration cell similar to the one shown below, except that both electrodes are made of Ni and in the left-hand compartment [Ni2+] = 1.0 M. Calculate the cell potential at 25°C when the concentration of Ni2+ in the compartment on the right has each of the following values.c. 0.10 MFor each case, also identify the cathode, anode, and the direction in which electrons flow.

An electrochemical cell is based on the following two half-reactions:Ox: Sn(s) →  Sn2+(aq, 1.80 M) + 2 e–Red: ClO2(g, 0.205 atm) + e– →  ClO2–(aq, 1.80 M)Compute the cell potential at 25 ˚C.

Consider a concentration cell similar to the one shown below, except that both electrodes are made of Ni and in the left-hand compartment [Ni2+] = 1.0 M. Calculate the cell potential at 25°C when the concentration of Ni2+ in the compartment on the right has each of the following values.d. 4.0 X 10 -5 MFor each case, also identify the cathode, anode, and the direction in which electrons flow.

A voltaic cell consists of a Zn/Zn2+ half-cell and a Ni/Ni2+ half-cell at 25 ˚C. The initial concentrations of Ni2+ and Zn2+ are 1.60 M and 0.120 M, respectively. The volume of half-cells is the same.What is the initial cell potential?

Consider a concentration cell similar to the one shown below, except that both electrodes are made of Ni and in the left-hand compartment [Ni2+] = 1.0 M. Calculate the cell potential at 25°C when the concentration of Ni2+ in the compartment on the right has each of the following values.e. Calculate the potential when both solutions are 2.5 M in Ni  2+.For each case, also identify the cathode, anode, and the direction in which electrons flow.

Consider the standard galvanic cell based on the following half-reactions:Cu2+ + 2e- → CuAg+ + e- → AgThe electrodes in this cell are Ag(s) and Cu(s). Does the cell potential increase, decrease, or remain the same when the following changes occur to the standard cell?a. CuSO4(s) is added to the copper half-cell compartment (assume no volume change).

A voltaic cell consists of a Zn/Zn2+ half-cell and a Ni/Ni2+ half-cell at 25 ˚C. The initial concentrations of Ni2+ and Zn2+ are 1.60 M and 0.120 M, respectively. The volume of half-cells is the same.What is the cell potential when the concentration of Ni2+ has fallen to 0.600 M?

A Cu/Cu2+ concentration cell has a voltage of 0.23 V at 25 ˚C. The concentration of Cu2+ in one of the half-cells is 1.6×10−3 M. What is the concentration of Cu2+ in the other half-cell? (Assume the concentration in the unknown cell to be the lower of the two concentrations.)

Consider the standard galvanic cell based on the following half-reactions:Cu2+ + 2e- → CuAg+ + e- → AgThe electrodes in this cell are Ag(s) and Cu(s). Does the cell potential increase, decrease, or remain the same when the following changes occur to the standard cell?b. NH3(aq) is added to the copper half-cell compartment. [Hint: Cu 2+ reacts with NH3 to form Cu(NH3)42+(aq).]

A voltaic cell consists of a Zn/Zn2+ half-cell and a Ni/Ni2+ half-cell at 25 ˚C. The initial concentrations of Ni2+ and Zn2+ are 1.60 M and 0.120 M, respectively. The volume of half-cells is the same.What is the concentrations of Ni2+ when the cell potential falls to 0.46 V?

Consider the standard galvanic cell based on the following half-reactions:Cu2+ + 2e- → CuAg+ + e- → AgThe electrodes in this cell are Ag(s) and Cu(s). Does the cell potential increase, decrease, or remain the same when the following changes occur to the standard cell?c. NaCl(s) is added to the silver half-cell compartment. [Hint: Ag + reacts with Cl - to form AgCl(s).]

A voltaic cell consists of a Zn/Zn2+ half-cell and a Ni/Ni2+ half-cell at 25 ˚C. The initial concentrations of Ni2+ and Zn2+ are 1.60 M and 0.120 M, respectively. The volume of half-cells is the same.What is the concentration of Zn2+ when the cell potential falls to 0.46 V?

Consider the standard galvanic cell based on the following half-reactions:Cu2+ + 2e- → CuAg+ + e- → AgThe electrodes in this cell are Ag(s) and Cu(s). Does the cell potential increase, decrease, or remain the same when the following changes occur to the standard cell?d. Water is added to both half-cell compartments until the volume of solution is doubled.

A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25 ˚C. The initial concentrations of Pb2+ and Cu2+ are 0.0520 M and 1.70 M, respectively.What is the initial cell potential?

A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25 ˚C. The initial concentrations of Pb2+ and Cu2+ are 0.0520 M and 1.70 M, respectively.What is the cell potential when the concentration of Cu2+ has fallen to 0.230 M?

A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25 ˚C. The initial concentrations of Pb2+ and Cu2+ are 0.0520 M and 1.70 M, respectively. What is the concentration of Pb2+ when the cell potential falls to 0.370 V?

A concentration cell consists of two Sn/Sn2+ half-cells. The cell has a potential of 0.15 V at 25 ˚C. What is the ratio of the Sn2+ concentrations in the two half-cells?

Determine the standard cell potential and the cell potential under the stated conditions for the electrochemical reactions described here. State whether each is spontaneous or nonspontaneous under each set of conditions at 298.15 K.(a) Hg(l) + S2−(aq, 0.10 M) + 2Ag+(aq, 0.25 M) ⟶ 2Ag(s) + HgS(s)

Determine the standard cell potential and the cell potential under the stated conditions for the electrochemical reactions described here. State whether each is spontaneous or nonspontaneous under each set of conditions at 298.15 K.(b) The galvanic cell made from a half-cell consisting of an aluminum electrode in 0.015 M aluminum nitrate solution and a half-cell consisting of a nickel electrode in 0.25 M nickel(II) nitrate solution.

Determine the standard cell potential and the cell potential under the stated conditions for the electrochemical reactions described here. State whether each is spontaneous or nonspontaneous under each set of conditions at 298.15 K.(c) The cell made of a half-cell in which 1.0 M aqueous bromide is oxidized to 0.11 M bromine ion and a half-cell in which aluminum ion at 0.023 M is reduced to aluminum metal. Assume the standard reduction potential for Br2(l) is the same as that of Br 2(aq).

Consider a battery made from one half-cell that consist of a copper electrode in 1 M CuSO4 solution and another half-cell that consist of a lead electrode in 1 M Pb(NO  3)2 solution.(d) Suppose sulfuric acid is added to the half-cell with the lead electrode and some PbSO 4(s) forms. Would the cell potential increase, decrease, or remain the same?

A voltaic cell is constructed that uses the following half-cell reactions:Cu+ (aq) + e-  →  Cu(s)I2 (s) + 2e-  →  2I- (aq)The cell is operated at 298 K with [Cu+ ] = 0.26 M and [I- ] = 3.6 M.(a) Determine E for the cell at these concentrations.(b) Which electrode is the anode of the cell?(c) Is the answer to part B the same as it would be if the cell was operated under standard conditions?

Consider a battery with the overall reaction: Cu(s) + 2Ag  +(aq) ⟶ 2Ag(s) + Cu 2+(aq).(b) A battery is “dead” when it has no cell potential. What is the value of Q when this battery is dead?

Consider a battery with the overall reaction: Cu(s) + 2Ag  +(aq) ⟶ 2Ag(s) + Cu 2+(aq).(c) If a particular dead battery was found to have [Cu2+] = 0.11 M, what was the concentration of silver ion?

Consider a voltaic cell whose overall reaction is Pb2+(aq) + Zn(s)  →  Pb(s) + Zn2+(aq). What is the emf generated by this voltaic cell when the ion concentrations are [Pb2+] = 1.5 10-3 M and [Zn2+] = 0.55 M?(a) 0.71 V(b) 0.56 V(c) 0.49 V(d) 0.79 V(e) 0.64 V

Consider a voltaic cell where the anode half-reaction is Zn(s)  →  Zn2+(aq) + 2 e- and the cathode half-reaction is Sn2+(aq) + 2 e–  →  Sn(s). What is the concentration of Sn2+ if Zn2+ is 2.5 X 10-3 M and the cell emf is 0.660 V? Use the reduction potentials in Appendix E that are reported to three significant figures. (a) 3.3 X 10-2 M(b) 1.9 X 10-4 M(c) 9.0 X 10-3 M(d) 6.9 X 10-4 M(e) 7.6 X 10-3 Marray{ { m Zn}^{+2}({ m aq})~+~2~{ m e}^-~& ightarrow &~ m Zn(s)~&~E^{circ}_{ m red}~&=&~-0.76~{ m V} cr { m Sn}^{2+}({ m aq})~+~2~{ m e}^–~& ightarrow &~ m Sn(s)~&~E^{circ}_{ m red}~&=&~-0.136~{ m V}}

A concentration cell constructed from two hydrogen electrodes, both with PH2 = 1.00. One electrode is immersed in pure H2O and the other in 6.0 M hydrochloric acid. What is the emf generated by the cell and what is the identity of the electrode that is immersed in hydrochloric acid?

The cell potential of the following electrochemical cell depends on the pH of the solution in the anode half-cell:Pt(s) | H2(g, 1 atm) | H+(aq, ? M) ‖ Cu2+(aq, 1.0 M) | Cu(s)What is the pH of the solution if Ecell is 370 mV ?

The cell potential of the following electrochemical cell depends on the gold concentration in the cathode half-cell:Pt(s) | H2(g, 1.0 atm) | H+(aq, 1.0 M) ‖ Au3+(aq, ? M) | Au(s)What is the concentration of Au3+ in the solution if Ecell is 1.26 V?

A battery is constructed based on the oxidation of magnesium and the reduction of Cu2+. The initial concentrations of Mg2+ and Cu2+ are 1.2×10−4 M and 1.6 M, respectively, in 1.0-liter half-cells. What is the initial voltage of the battery?

Two concentration cells are prepared, both with 90.0 mL of 0.0100 M Cu(NO 3)2 and a Cu bar in each half-cell.(a) In the first concentration cell, 10.0 mL of 0.500 M NH 3 is added to one half-cell; the complex ion Cu(NH3)42+ forms, and Ecell is 0.129 V. Calculate K f for the formation of the complex ion.

A voltaic cell employs the following redox reaction: 2 Fe3+(aq) + 3 Mg(s)  →  2 Fe(s) + 3 Mg2+(aq)Calculate the cell potential at 25 ˚C under each of the following conditions: [Fe3+] = 1.8×10−3 M; [Mg2+] = 2.55 M

Two concentration cells are prepared, both with 90.0 mL of 0.0100 M Cu(NO 3)2 and a Cu bar in each half-cell.(b) Calculate Ecell when an additional 10.0 mL of 0.500 M NH 3 is added.

A voltaic cell employs the following redox reaction: 2 Fe3+(aq) + 3 Mg(s)  →  2 Fe(s) + 3 Mg2+(aq)Calculate the cell potential at 25 ˚C under each of the following conditions: [Fe3+] = 2.55 M; [Mg2+] = 1.8×10−3 M

Two concentration cells are prepared, both with 90.0 mL of 0.0100 M Cu(NO 3)2 and a Cu bar in each half-cell.(c) In the second concentration cell, 10.0 mL of 0.500 M NaOH is added to one half-cell; the precipitate Cu(OH)2 forms (Ksp = 2.2 × 10−20). Calculate E°cell.

Two concentration cells are prepared, both with 90.0 mL of 0.0100 M Cu(NO 3)2 and a Cu bar in each half-cell.(d) What would the molarity of NaOH have to be for the addition of 10.0 mL to result in an E° cell of 0.340 V?

The Ksp of CuI is 1.1×10−12. Find Ecell for the following cell: Cu(s) | CuI(s) | I–(aq) (1 M) ‖ Cu+ (aq) (1 M) | Cu(s).

A voltaic cell has one half-cell with a Cu bar in a 1.00 M Cu  2+ salt, and the other half-cell with a Cd bar in the same volume of a 1.00 M Cd2+ salt.(b) As the cell operates, [Cd 2+] increases; find Ecell and ΔG when [Cd 2+] is 1.95 M.

An MnO2(s)/Mn2+(aq) electrode in which the pH is 10.25 is prepared. Find the [Mn2+] necessary to lower the potential of the half-cell to 0.00 V (at 25 ˚C).

A voltaic cell designed to measure [Cu2+] is constructed of a standard hydrogen electrode and a copper metal electrode in the Cu2+ solution of interest. If you wanted to construct a calibration curve for how the cell potential varies with the concentration of copper(II), what would you plot in order to obtain a straight line?

A voltaic cell designed to measure [Cu2+] is constructed of a standard hydrogen electrode and a copper metal electrode in the Cu2+ solution of interest. What would be the slope of the line?

Find Ecell for an electrochemical cell based on the following reaction with [MnO4–] = 1.80 M, [H+] = 1.30 M, and [Ag+] = 0.0110 M. E˚cell for the reaction is +0.880 V.MnO4–(aq) + 4 H+(aq) + 3 Ag(s) → MnO2(s) + 2 H2O(l) + 3 Ag+(aq)

Use the Nernst equation to show that Ecell = E˚cell under standard conditions.

A galvanic cell is based on the following half-reactions at 25°C:Ag+ + e- → AgH2O2 + 2H+ + 2e- → 2H2OPredict whether Ecell is larger or smaller than E°cell for the following cases.a. [Ag+] = 1.0 M, [H2O2] = 2.0 M, [H+] = 2.0 M

A galvanic cell is based on the following half-reactions at 25°C:Ag+ + e- → AgH2O2 + 2H+ + 2e- → 2H2OPredict whether Ecell is larger or smaller than E°cell for the following cases.b. [Ag+] = 2.0 M, [H2O2] = 1.0 M, [H+] = 1.0 x 10 -7 M

Relationships of E°, ΔG°, and K. Any one of these important parameters can be used to calculate the other two. The signs of E° and ΔG° determine the direction that the reaction proceeds under standard conditions. The magnitude of { m K} determines the relative amounts of reactants and products in an equilibrium mixture.What does the variable n represent in the ΔG° and E° equations?

Consider the concentration cell in Fig. 17‑10. If the Fe 2+ concentration in the right compartment is changed from 0.1 M to 1 x 10-7 M Fe2+, predict the direction of electron flow, and designate the anode and cathode compartments.

Consider the concentration cell shown below. Calculate the cell potential at 25°C when the concentration of Ag+ in the compartment on the right is the following.a. 1.0 MFor each case, also identify the cathode, the anode, and the direction in which electrons flow.

Consider the reaction shown here occurring at 25 ˚C:Cr(s) + Cd2+(aq) →  Cr2+(aq) + Cd(s)Complete the table.[Cd2+][Cr2+]QEcellΔGrxn1.001.001.001.00 x 10-51.0 x 10-51.004.18x10-41.00Note: Cr(s)  →  Cr2+(aq) + 2 e-, Ered = –0.91 VDetermine Q, Ecell, and ΔGrxn for the second row of the table.

Consider the concentration cell shown below. Calculate the cell potential at 25°C when the concentration of Ag+ in the compartment on the right is the following.b. 2.0 MFor each case, also identify the cathode, the anode, and the direction in which electrons flow.

Consider the reaction shown here occurring at 25 ˚C:Cr(s) + Cd2+(aq) →  Cr2+(aq) + Cd(s)Complete the table.[Cd2+][Cr2+]QEcellΔGrxn1.001.001.001.00 x 10-51.0 x 10-51.004.18x10-41.00Note: Cr(s)  →  Cr2+(aq) + 2 e-, Ered = –0.91 VDetermine Q, Ecell, and ΔGrxn for the third row of the table.

Consider the concentration cell shown below. Calculate the cell potential at 25°C when the concentration of Ag+ in the compartment on the right is the following.c. 0.10 MFor each case, also identify the cathode, the anode, and the direction in which electrons flow.

Consider the reaction shown here occurring at 25 ˚C:Cr(s) + Cd2+(aq) →  Cr2+(aq) + Cd(s)Complete the table.[Cd2+][Cr2+]QEcellΔGrxn1.001.001.001.00 x 10-51.0 x 10-51.004.18x10-41.00Note: Cr(s)  →  Cr2+(aq) + 2 e-, ;;;; Ered = –0.91 VDetermine Q, Ecell, and ΔGrxn for the fourth row of the table.

Consider the concentration cell shown below. Calculate the cell potential at 25°C when the concentration of Ag+ in the compartment on the right is the following.d. 4.0 x 10 -5 MFor each case, also identify the cathode, the anode, and the direction in which electrons flow.

Consider the concentration cell shown below. Calculate the cell potential at 25°C when the concentration of Ag+ in the compartment on the right is the following.e. Calculate the potential when both solutions are 0.10 M in Ag  +.For each case, also identify the cathode, the anode, and the direction in which electrons flow.

Consider a concentration cell similar to the one shown below, except that both electrodes are made of Ni and in the left-hand compartment [Ni2+] = 1.0 M. Calculate the cell potential at 25°C when the concentration of Ni2+ in the compartment on the right has each of the following values.a. 1.0 MFor each case, also identify the cathode, anode, and the direction in which electrons flow.

The overall reaction in the lead storage battery isPb(s) + PbO2 (s) + 2H +(aq) + 2HSO4 -(aq) → 2PbSO4 (s) + 2H2O(l)Calculate ε at 25°C for this battery when [H 2SO4] = 4.5 M, that is, [H +] = [HSO4 -] = 4.5 M. At 25°C, ε ° = 2.04 V for the lead storage battery.

Consider the half reaction Ag+ ( aq ) + e-  →  Ag( s ).What is the value of Ered when log[Ag+] = 0?

Consider the cell described below:Zn | Zn 2+(1.00 M) ‖ Cu 2+(1.00 M) | CuCalculate the cell potential after the reaction has operated long enough for the [Zn 2+] to have changed by 0.20 mol/L. (Assume T = 25°C.)

Consider the reaction shown here occurring at 25 ˚C:A(s) + B2+(aq) →  A2+(aq) + B(s), ΔG˚rxn = –14.0 kJComplete the table.[B2+][A2+]QEcellΔGrxn1.001.001.001.00 x 10-41.0 x 10-41.03.54 x 10-31.0Determine Q, Ecell, and ΔGrxn for the second row of the table.

Consider the cell described below:Al | Al 3+(1.00 M) ‖ Pb 2+(1.00 M) | PbCalculate the cell potential after the reaction has operated long enough for the [Al  3+] to have changed by 0.60 mol/L. (Assume T = 25°C.)

Consider the reaction shown here occurring at 25 ˚C:A(s) + B2+(aq) →  A2+(aq) + B(s), ΔG˚rxn = –14.0 kJComplete the table.[B2+][A2+]QEcellΔGrxn1.001.001.001.00 x 10-41.0 x 10-41.03.54 x 10-31.0Determine Q, Ecell, and ΔGrxn for the third row of the table.

Consider the reaction shown here occurring at 25 C:A(s) + B2+(aq) →  A2+(aq) + B(s), ΔG˚rxn = –14.0 kJComplete the table.[B2+][A2+]QEcellΔGrxn1.001.001.001.00 x 10-41.0 x 10-41.03.54 x 10-31.0Determine Q, Ecell, and ΔGrxn for the fourth row of the table.

Consider the galvanic cell based on the following half-reaction:Zn2+ + 2e- → Zn      ε° = —0.76 VFe2+ + 2e- → Fe      ε° = —0.44 Vc. Calculate ε°cell at 25°C when [Zn 2+] = 0.10 M and [Fe 2+] = 1.0 X 10 -5 M.

Consider the galvanic cell based on the following half-reaction:Au3+ + 3e- → Au           ε° = 1.50 V      Tl + + e- → Tl            ε° = —0.34 Vc. Calculate ε°cell  at 25°C when [Au 3+] = 1.0 X 10 -2 M and [Tl +] = 1.0 X 10 -4 M.

An electrochemical cell consist of a standard hydrogen electrode and a copper metal electrode.a. What is the potential of the cell at 25°C if the copper electrode is placed in a solution in which [Cu2+] = 2.5 X 10 -4 M?

Design a device that uses an electrochemical cell to determine the amount of Cu2+ in a sample of water. If you are able to measure voltage with one-millivolt accuracy, what will the uncertainty in your measured concentration be?

An electrochemical cell consists of a standard hydrogen electrode and a copper metal electrode.b. The copper electrode is placed in a solution of unknown [Cu  2+]. The measured potential at 25°C is 0.195 V. What is [Cu2+]? (Assume Cu 2+ is reduced.)

An electrochemical cell consists of a nickel metal electrode immersed in a solution with [Ni2+] = 1.0 M separated by a porous disk from an aluminum metal electrode.a. What is the potential of this cell at 25°C if the aluminum electrode is placed in a solution in which [Al3+] = 7.2 X 10-3 M?

An electrochemical cell consists of a nickel metal electrode immersed in a solution with [Ni2+] = 1.0 M separated by a porous disk from an aluminum metal electrode.b. When the aluminum electrode is placed in a certain solution in which [Al  3+] is unknown, the measured cell potential at 25°C is 1.62 V. Calculate [Al 3+] in the unknown solution. (Assume Al is oxidized.)

An electrochemical cell consists of a standard hydrogen electrode and a copper metal electrode. If the copper electrode is placed in a solution of 0.10 M NaOH that is saturated with Cu(OH)2, what is the cell potential at 25°C? [For Cu(OH) 2, Ksp = 1.6 X 10 -19.]

You have a concentration cell in which the cathode has a silver electrode with 0.10 M Ag+. The anode also has a silver electrode with Ag +(aq), 0.050 M S 2O3 2-, and 1.0 X 10 -3 M Ag(S2O3)2 3-. You read the voltage to be 0.76 V.a. Calculate the concentration of Ag + at the anode.

Using a library or the Internet, research a fuel cell that uses methanol for fuel. How many kWh can it generate from 1 L (0.792 kg) of methanol?

Consider the following galvanic cell at 25°C:Pt | Cr 2+  (0.30 M), Cr 3+ (2.0 M) | | Co 2+ (0.20 M) | CoThe overall reaction and equilibrium constant value are2Cr 2+(aq) + Co 2+(aq) → 2Cr 3+ (aq) + Co(s)    K = 2.79 X 10 7Calculate the cell potential, ε, for this galvanic cell and ΔG for the cell reaction at these conditions.

An electrochemical cell consists of a silver metal electrode immersed in a solution with [Ag +] = 1.0 M separated by a porous disk from a copper metal electrode. If the copper electrode is placed in a solution of 5.0 M NH3 that is also 0.010 M in Cu(NH 3)4 2+, what is the cell potential at 25°C?Cu2+(aq) + 4NH3 (aq) ⇌ Cu(NH 3)4 2+(aq)          K = 1.0 X 10 13

In the Nernst equation, what is the numerical value of the reaction quotient, Q, under standard conditions?

Can the Nernst equation be used at temperatures other than room temperature?

To examine the effect of ion removal on cell voltage, a chemist constructs two voltaic cells, each with a standard hydrogen electrode in one compartment. One cell also contains a Pb/Pb2+ half-cell; the other contains a Cu/Cu2+ half-cell.(d) When sufficient Na2S is added to the Cu2+ electrolyte, CuS forms and [Cu2+] drops to 1 × 10−16 M. Find the cell voltage.

Consider a galvanic cell based on the following half-reactions:b. A nonstandard cell is set up at 25°C with [Mg 2+] = 1.00 x 10 -5 M. The cell potential is observed to be 4.01 V. Calculate [Au3+] in this cell.

A voltaic cell is constructed that is based on the following reaction:Sn2+ (aq) + Pb(s)  →  Sn(s) + Pb2 +  (aq)If the concentration of Sn2+ in the cathode compartment is 1.00 M and the cell generates an emf of +0.22 V , what is the concentration of Pb2+ in the anode compartment?

Consider the half reaction Ag+ ( aq ) + e-  →  Ag( s ).  Which of the lines in the following diagram indicates how the reduction potential varies with the concentration of Ag+?

A voltaic cell is constructed with two silver-silver chloride electrodes, each of which is based on the following half-reaction:AgCl(s) + e-  →  Ag(s) + Cl- (aq).The two cell compartments have [Cl- ] = 1.51×10−2 M and [Cl- ] = 2.60 M , respectively.For the cathode compartment, predict whether [Cl- ] will increase, decrease, or stay the same as the cell operates.

A voltaic cell is constructed froman Ni2 +  (aq) - Ni(s) half-cell andan Ag+ (aq) - Ag(s) half-cell.The initial concentration of Ni2 +  (aq) in the Ni2 +   - Ni half-cell is [Ni2 +  ] = 1.50×10−2 M . The initial cell voltage is +1.13 V .By using data in Table 20.1 in the textbook, calculate the standard emf of this voltaic cell.

Calculate the standard potential, E°, for this reaction from its equilibrium constant at 298 K.X(s) + Y2+(aq) ⇌ X2+(aq) + Y(s)   K= 9.49 x 105

Consider this reaction.Sn2+ (aq) + 2 Fe3+ (aq) → Sn4+ (aq) + 2 Fe2+ (aq)     E° = 0.617 VWhat is the value of E when [Sn2+] and {Fe3+] are equal to 0.50 M and [Sn4+] and [Fe2+] are equal to 0.10 M?(A) 0.069V(B) 0.679 V(C) 0.658 V(D) 0.576

A voltaic cell consists of a Pb/ Pb2+ half-cell and a Cu/Cu2+ half-cell at 25°C. The initial concentrations of Pb2+ and Cu2+ are 0.0500 M and 1.50 M, respectively.a. What is the initial cell potential?

A concentration cell consists of two Sn/Sn2+ half-cells. The cell has a potential of 0.15V at 25°C. What is the ratio of the Sn2+ concentrations in the two half-cells? 

The voltage generated by the zinc concentration cell described by,Zn(s)|Zn2+ (aq, 0.100 M)||Zn2+ (aq, ? M)|Zn(s)is 18.0 mV at 25°C. Calculate the concentration of the Zn2+ (aq) ion at the cathode.

Given the measured cell potential, Ecell, is -0.3641 V at 25 °C in the following cell, calculate the H+ concentration Pt (s) | H2(g, 0.769 atm) | H+ (aq, ? M) || Cd2+ (aq, 1.00 M) | Cd(s) The balanced reduction half-reactions for the cell, and their respective standard reduction potential values, E°, are as follows. 2H+(aq) + 2e- → H2(g)                  E° = 0.00 V Cd2+ (aq) + 2e- → Cd(s)               E° = -0.403 V

Calculate the standard potential, E°, for this reaction from its equilibrium constant at 298 K.X(s) + Y3+(aq) ⇌ X3+(aq) + Y(s)          K= 2.12 x 10 -5