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Zorluk: OrtaElectrochemical Series and Reaction Spontaneity
The standard reduction potentials for tin and silver half-cells are given below:
Sn2+(aq)+2eSn(s)E=0.14 V\text{Sn}^{2+}(aq) + 2e^- \rightarrow \text{Sn}(s) \quad E^\circ = -0.14\text{ V}
Ag+(aq)+eAg(s)E=+0.80 V\text{Ag}^+(aq) + e^- \rightarrow \text{Ag}(s) \quad E^\circ = +0.80\text{ V}
What is the standard cell potential (EcellE^\circ_{\text{cell}}) for the overall redox reaction:
Sn(s)+2Ag+(aq)Sn2+(aq)+2Ag(s)\text{Sn}(s) + 2\text{Ag}^+(aq) \rightarrow \text{Sn}^{2+}(aq) + 2\text{Ag}(s)
  1. +0.94 V+0.94\text{ V}Cevap
  2. B
    +0.66 V+0.66\text{ V}
  3. C
    0.94 V-0.94\text{ V}
  4. D
    +1.74 V+1.74\text{ V}

Cevap

+0.94 V+0.94\text{ V}
In the given cell reaction, silver ions undergo reduction at the cathode (E=+0.80 VE^\circ = +0.80\text{ V}) while tin metal undergoes oxidation at the anode (E=0.14 VE^\circ = -0.14\text{ V}). The standard cell potential is calculated using Ecell=EcathodeEanode=+0.80 V(0.14 V)=+0.94 VE^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} = +0.80\text{ V} - (-0.14\text{ V}) = +0.94\text{ V}. Because EE^\circ values are intensive properties, the stoichiometric multiplier for the silver half-reaction does not scale its potential value.

Adım Adım Çözüm

1
Identify the reduction and oxidation half-reactions from the given reaction equation.
Tin metal (Sn\text{Sn}) is oxidized to Sn2+\text{Sn}^{2+} at the anode, while silver ions (Ag+\text{Ag}^+) are reduced to silver metal at the cathode.
Oxidation occurs at the anode (loss of electrons) and reduction occurs at the cathode (gain of electrons).
2
Apply the formula for standard cell potential Ecell=EcathodeEanodeE^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}}.
Ecell=(+0.80 V)(0.14 V)=+0.80 V+0.14 V=+0.94 VE^\circ_{\text{cell}} = (+0.80\text{ V}) - (-0.14\text{ V}) = +0.80\text{ V} + 0.14\text{ V} = +0.94\text{ V}.
Standard electrode potentials are intensive properties and are not multiplied by stoichiometric coefficients.

Anahtar Kavram

Calculation of Standard Cell Potential and Reaction Spontaneity
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