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General Chemistry Principles, Patterns, and Applications, 2011

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. What is the highest pH at which this reaction will proceed spontaneously if [Fe 3+ ] = [FeO 2− 4 ]<br />

= 1.0 M an d PO2 =<br />

c. 1.0 atm?<br />

21. Under acidic conditions, ideally any half-reaction with E° > 1.23 V will oxidize water via the reaction O 2 (g) +<br />

4H + (aq) + 4e − → 2H 2 O(l).<br />

a. Will aqueous acidic KMnO 4 evolve oxygen with the formation of MnO 2 ?<br />

b. At pH 14.00, what is E° for the oxidation of water by aqueous KMnO 4 (1 M) with the<br />

formation of MnO 2 ?<br />

c. At pH 14.00, will water be oxidized if you are trying to form MnO 2 from MnO 2− 4 via the<br />

reaction 2MnO 2− 4 (aq) + 2H 2 O(l) → 2MnO 2 (s) + O 2 (g) + 4OH − (aq)?<br />

22. Complexing agents can bind to metals <strong>and</strong> result in the net stabilization of the complexed species. What is<br />

23.<br />

24.<br />

the net thermodynamic stabilization energy that results from using CN − as a complexing agent for Mn 3+ /Mn 2+ ?<br />

( ) + e- ® Mn2 + aq<br />

( ) + e- ® Mn CN<br />

Mn3+ aq<br />

Mn( CN )63- aq<br />

( )E° = 1.51 V<br />

( )64 - E° = -0.24 V<br />

25. You have constructed a cell with zinc <strong>and</strong> lead amalgam electrodes described by the cell diagram<br />

Zn(Hg)(s)∣ Zn(NO 3 ) 2 (aq)∥ Pb(NO 3 ) 2 (aq)∣ Pb(Hg)(s). If you vary the concentration of Zn(NO 3 ) 2 <strong>and</strong> measure the<br />

potential at different concentrations, you obtain the following data:<br />

Zn(NO3)2 (M) Ecell (V)<br />

0.0005 0.7398<br />

0.002 0.7221<br />

0.01 0.7014<br />

a. Write the half-reactions that occur in this cell.<br />

b. What is the overall redox reaction?<br />

c. What is E° cell ? What is ΔG° for the overall reaction?<br />

d. What is the equilibrium constant for this redox reaction?<br />

26. Hydrogen gas reduces Ni 2+ according to the following reaction: Ni 2+ (aq) + H 2 (g) → Ni(s) + 2H + (aq); E° cell = −0.25<br />

V; ΔH = 54 kJ/mol.<br />

a. What is K for this redox reaction?<br />

b. Is this reaction likely to occur?<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

1777

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