Concept:The standard Electromotive Force (EMF) of a cell is calculated by subtracting the reduction potential of the anode from the reduction potential of the cathode.
Formula:$$E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode}$$
Solution:- First, identify the anode and cathode based on standard reduction potentials.
- Ag has a higher reduction potential (\( +0.80 \text{ V} \)), so it acts as the cathode (reduction).
- Al has a lower reduction potential (\( -1.67 \text{ V} \)), so it acts as the anode (oxidation).
- Apply the formula: \( E^\circ_{cell} = (+0.80 \text{ V}) - (-1.67 \text{ V}) \).
- \( E^\circ_{cell} = 0.80 + 1.67 = 2.47 \text{ V} \).
Why other options are incorrect:If one incorrectly subtracted the larger from the smaller, they would get a negative voltage. Standard galvanic cell potentials are always positive.
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