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  

Consider this reaction. Sn2+ (aq) + 2 Fe3+ (aq) → Sn4+ (aq) + 2 Fe2+ (aq)     E° = 0.617 V What 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 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. a. What is the ini tial cell pote nti al?

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?  

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.

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 a 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)