Consider the data in the table below and an electrochemical cell where the follo

Question

Consider the data in the table below and an electrochemical cell where the following unbalanced chemical reaction takes place: __________ Au^1+ (aq) + __________ Zn(s) rightarrow ___________ Au (s) + ______________ Zn^2+ (aq) How many total electrons are transferred in this redox reaction? 4 3 2 1 Which of the following represents the correct line notation for this cell? Au[s][Au^1+ (aq)|| Zn^2+ (aq) | Zn(s) Au^1+ (aq)|Au(s) || Zn (s) | Zn^2+ (aq) Zn^2+ (aq) |Zn(s) || Au (s) | Zu^1+ (aq) Zn (s) | Au^1+ (aq)||Zu^2+ (aq) | Au (s) Zn (s) | Zn^2+ (aq) || Au^1+ (aq)| Au (s) If the cell voltage under standard conditions (E^0 _ cell) = 2.44 V, what is the standard reduction potential for the reduction of Au^+1? 1.68 V -1.68 V +3.2 V -3.2 V Which of the following statements about this cell are correct? The reaction is spontaneous because delta G^degree = -235 kJ The reaction is spontaneous because delta G^dot = -471 kJ The reaction is non-spontaneous because delta G^degree = -471 kJ The reaction is non-spontaneous because delta G^degree = -235 kJ What will a voltmeter read, if you operate the cell at 40 degree C using a 0.031 M AuNo_3, solution and a 0.28 M Zn (NO_3)_2 solution? 2.52 V 2.46 V 2.44 V 2.41 V 2.36 V Now consider only the gold half-cell. How many grams of gold could be plated out of the solution if a current of 0.5 Amps is passed through a 1.19 M AuNO_3 solution for 30 minutes? 17.9 g 3.67 g 2.38 g 1.84 g

Explanation / Answer

5) 2Au1+ + e- + Zn ---> Au2 + Zn2+ + 2e-

2 electron transfer

6)Ecell = Eanode //Ecathode

so Zn/Zn2+// Au+/Au

7) Ecell = Ecathode - Eanode

2.44 = Ecathode - (-0.76 V)

Ecathode = 1.68 V

8) delta G = -n F Ecell

delta G = -2 x 96500 x 2.44 V

delta G = -470.92 KJ < 0 so spontaneous

9) Ecell = E0cell - (0.059 /n) log[0.28 M]/[0.031M]

Ecell = 2.44 V - (0.059/2) (log[0.28/0.031] )

Ecell = 2.41 v

10) W = Z i t {i = current , t = time, Z= eq.wt of sub/96500}

W = 0.5 x 30 min x (1.19/96500)

W = 0.00018497

W = 1.84 g

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