A physical science student is building a battery with two metal plates. The table below shows a list of metals and their electron affinities:

\begin{tabular}{|l|l|}
\hline
Metal & Electron Affinity (electron volts, [tex][tex]$e V$[/tex][/tex]) \\
\hline
Sodium & -2.71 \\
\hline
Magnesium & -2.31 \\
\hline
Silver & +0.80 \\
\hline
Platinum & +1.20 \\
\hline
\end{tabular}

The student has a silver plate. When paired with silver, which metal plate will produce a higher voltage?

A. Sodium
B. Magnesium
C. Silver
D. Platinum



Answer :

Let's solve the problem step by step:

1. Understand the Concept:
- Electron Affinity: In this context, electron affinity is the value that reflects the energy change when an electron is added to a neutral atom. Positive values indicate energy release when an atom gains an electron, while negative values indicate energy absorption.

- Voltage Production: The voltage produced in a battery can be related to the difference in electron affinities between two metals.

2. Extract Important Information:
- We are given the electron affinities of different metals.
- Sodium: [tex]\( -2.71 \)[/tex] eV
- Magnesium: [tex]\( -2.31 \)[/tex] eV
- Silver: [tex]\( +0.80 \)[/tex] eV
- Platinum: [tex]\( +1.20 \)[/tex] eV

- The task is to find out which metal, when paired with silver, produces the highest voltage.

3. Calculate the Voltage Produced:
- Voltage with Sodium:
- Voltage = [tex]\( \text{abs}(0.80 - (-2.71)) \)[/tex]
- Simplifying: [tex]\( \text{Voltage}_{\text{Sodium}} = 3.51 \)[/tex] eV

- Voltage with Magnesium:
- Voltage = [tex]\( \text{abs}(0.80 - (-2.31)) \)[/tex]
- Simplifying: [tex]\( \text{Voltage}_{\text{Magnesium}} = 3.11 \)[/tex] eV

- Voltage with Silver:
- Voltage = [tex]\( \text{abs}(0.80 - 0.80) \)[/tex]
- Simplifying: [tex]\( \text{Voltage}_{\text{Silver}} = 0.00 \)[/tex] eV

- Voltage with Platinum:
- Voltage = [tex]\( \text{abs}(0.80 - 1.20) \)[/tex]
- Simplifying: [tex]\( \text{Voltage}_{\text{Platinum}} = 0.40 \)[/tex] eV

4. Compare the Calculated Voltages:
- Sodium: [tex]\( 3.51 \)[/tex] eV
- Magnesium: [tex]\( 3.11 \)[/tex] eV
- Silver: [tex]\( 0.00 \)[/tex] eV
- Platinum: [tex]\( 0.40 \)[/tex] eV

So, the highest voltage is produced when the silver plate is paired with the sodium plate, resulting in a voltage of [tex]\( 3.51 \)[/tex] eV.

Answer: Sodium

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