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Ch.20 - Electrochemistry
Chapter 20, Problem 55

Make a sketch of the voltaic cell represented by the line notation. Write the overall balanced equation for the reaction and calculate E°cell. Sn(s) | Sn2+(aq) || NO(g) | NO3(aq), H+(aq) | Pt(s)

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Identify the anode and cathode components from the line notation. The anode is where oxidation occurs and is represented on the left side of the double vertical lines (||). In this case, Sn(s) | Sn2+(aq) is the anode half-cell, and NO(g) | NO3-(aq), H+(aq) | Pt(s) is the cathode half-cell.
Write the half-reactions for both the anode and cathode. For the anode, the oxidation reaction is Sn(s) → Sn2+(aq) + 2e-. For the cathode, the reduction reaction is NO3-(aq) + 4H+(aq) + 3e- → NO(g) + 2H2O(l).
Balance the overall cell reaction by equalizing the number of electrons transferred in the oxidation and reduction half-reactions. Multiply the anode reaction by 3 and the cathode reaction by 2 to balance the electrons: 3Sn(s) → 3Sn2+(aq) + 6e- and 2NO3-(aq) + 8H+(aq) + 6e- → 2NO(g) + 4H2O(l).
Add the balanced half-reactions to get the overall cell reaction: 3Sn(s) + 2NO3-(aq) + 8H+(aq) → 3Sn2+(aq) + 2NO(g) + 4H2O(l).
Calculate the standard cell potential, Ec°ell, using the standard reduction potentials of the cathode and anode. Ec°ell = Ec°(cathode) - Ec°(anode). Look up the standard reduction potentials for each half-reaction in a table of standard potentials.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Voltaic Cell

A voltaic cell, also known as a galvanic cell, is an electrochemical cell that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two half-cells, each containing an electrode and an electrolyte. The flow of electrons from the anode to the cathode generates an electric current, which can be harnessed for external use.
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Standard Electrode Potential (E°)

The standard electrode potential (E°) is a measure of the tendency of a chemical species to be reduced, measured under standard conditions (1 M concentration, 1 atm pressure, and 25°C). It is expressed in volts and is used to calculate the overall cell potential (E°cell) for electrochemical reactions. The more positive the E° value, the greater the species' ability to gain electrons and undergo reduction.
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Nernst Equation

The Nernst equation relates the cell potential (E) to the standard electrode potential (E°) and the concentrations of the reactants and products involved in the electrochemical reaction. It is given by E = E° - (RT/nF) ln(Q), where R is the gas constant, T is the temperature in Kelvin, n is the number of moles of electrons transferred, F is Faraday's constant, and Q is the reaction quotient. This equation allows for the calculation of cell potential under non-standard conditions.
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