(a) Based on standard reduction potentials, would you expect copper metal to oxidize under standard conditions in the presence of oxygen and hydrogen ions? (b) When the Statue of Liberty was refurbished, Teflon spacers were placed between the iron skeleton and the copper metal on the surface of the statue. What role do these spacers play?

Short Answer

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(a) Yes, under standard conditions, copper metal will oxidize in the presence of oxygen and hydrogen ions, as the total standard reduction potential for the reaction is positive, with a value of +0.89V. (b) The Teflon spacers placed between the iron skeleton and the copper metal on the surface of the Statue of Liberty prevent galvanic corrosion. They act as an insulator, avoiding direct contact between the two metals and thereby eliminating the possibility of galvanic corrosion, ensuring the monument's longevity and structural integrity.

Step by step solution

01

(a) Determine if Copper will Oxidize in the Presence of Oxygen and Hydrogen Ions under Standard Conditions

To determine if copper will oxidize in the presence of oxygen and hydrogen ions under standard conditions, we should compare the standard reduction potentials of the half-reactions. The relevant half-reactions are: 1. \(Cu^{2+}(aq) + 2e^{-} ⟶ Cu(s)\) - standard reduction potential (SRP) = +0.34 V 2. \(O_2(g) + 4H^{+}(aq) + 4e^{-} ⟶ 2H_2O(l)\) - standard reduction potential (SRP) = +1.23 V If the sum of the standard reduction potentials is positive, the reaction is spontaneous, meaning the oxidation of copper will occur. In order to find out if the reaction is spontaneous, the half-reactions must be added together, where the second reaction is kept as it is, and the first reaction is reversed (oxidation). The reversed reaction for the first half-reaction is as follows: 3. \(Cu(s) ⟶ Cu^{2+}(aq) + 2e^{-}\) with a standard reduction potential of -0.34V. Now, we will add the half-reactions and their corresponding standard reduction potentials: 4. \( Cu(s) + O_2(g) + 4H^{+}(aq) ⟶ Cu^{2+}(aq) + 2H_2O(l)\) with a total SRP = -0.34V + 1.23V = +0.89V Since the total standard reduction potential is positive (+0.89V), the reaction is spontaneous and copper will oxidize under standard conditions in the presence of oxygen and hydrogen ions.
02

(b) Role of Teflon Spacers in the Refurbishment of the Statue of Liberty

The Statue of Liberty is made of copper, and its supporting structure is made of iron. When two metals with different standard reduction potentials (like copper and iron) come into contact in the presence of moisture, a process called galvanic corrosion can occur. In this process, the metal with a lower reduction potential (iron in this case) will corrode, while the metal with a higher reduction potential (copper) will be protected. Teflon spacers were placed between the iron skeleton and the copper metal on the surface of the Statue of Liberty during its refurbishment to prevent this galvanic corrosion. These spacers act as an insulator, preventing direct contact between the copper and iron metals, and thus eliminating the possibility of galvanic corrosion. This helps to ensure the longevity and structural integrity of both the copper surface and the iron supporting structure, preserving the monument for future generations to appreciate.

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Most popular questions from this chapter

(a) Suppose that an alkaline battery was manufactured using cadmium metal rather than zinc. What effect would this have on the cell emf? (b) What environmental advantage is provided by the use of nickel-metal hydride batteries over nickel-cadmium batteries?

A mixture of copper and gold metals that is subjected to electrorefining contains tellurium as an impurity. The standard reduction potential between tellurium and its lowest common oxidation state, \(\mathrm{Te}^{4+},\) is $$ \mathrm{Te}^{4+}(a q)+4 \mathrm{e}^{-} \longrightarrow \mathrm{Te}(s) \quad E_{\mathrm{red}}^{\circ}=0.57 \mathrm{V} $$ Given this information, describe the probable fate of tellurium impurities during electrorefining. Do the impurities fall to the bottom of the refining bath, unchanged, as copper is oxidized, or do they go into solution as ions? If they go into solution, do they plate out on the cathode?

(a) What is an electrolytic cell? (b) The negative terminal of a voltage source is connected to an electrode of an electrolytic cell. Is the electrode the anode or the cathode of the cell? Explain. (c) The electrolysis of water is often done with a small amount of sulfuric acid added to the water. What is the role of the sulfuric acid? (d) Why are active metals such as Al obtained by electrolysis using molten salts rather than aqueous solutions?

Cytochrome, a complicated molecule that we will represent as CyFe \(^{2+},\) reacts with the air we breathe to supply energy required to synthesize adenosine triphosphate (ATP). The body uses ATP as an energy source to drive other reactions (Section 19.7). At pH 7.0 the following reduction potentials pertain to this oxidation of \(\mathrm{CyFe}^{2+} :\) $$ \begin{aligned} \mathrm{O}_{2}(g)+4 \mathrm{H}^{+}(a q)+4 \mathrm{e}^{-} \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(l) & E_{\mathrm{red}}^{\circ}=+0.82 \mathrm{V} \\ \mathrm{CyFe}^{3+}(a q)+\mathrm{e}^{-} \longrightarrow \mathrm{CyFe}^{2+}(a q) & E_{\mathrm{red}}^{\circ}=+0.22 \mathrm{V} \end{aligned} $$ (a) What is \(\Delta G\) for the oxidation of CyFe \(^{2+}\) by air? (b) If the synthesis of 1.00 mol of ATP from adenosine diphosphate (ADP) requires a \(\Delta G\) of 37.7 \(\mathrm{kJ}\) , how many moles of ATP are synthesized per mole of \(\mathrm{O}_{2} ?\)

(a) What is meant by the term reduction? (b) On which side of a reduction half-reaction do the electrons appear? (c) What is meant by the term reductant? (d) What is meant by the term reducing agent?

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