Accidentally chewing on a stray fragmet of aluminium foil can causes a sharp tooth path if the aluminium comes in contact with an amalgam filing. The filing, an alloy of silver, tin and mercury, acts as the cathode of a tiny galvanic cell, the aluminium behaves as the anode, and salivas serves as the electrolyte. when the aluminium and the filling come in contact, and electric current passage from the aluminium to the filling which is sensed by a nerve in the tooth. Aluminium is oxidized at the anode, and `O_(2)` gas is reduced to water at the cathode.
`E_(AI^(3+)//AI)^(@) =- 1.66 E_(O_(2)H^(+)//H_(2)O)6^(@) = 1.23 V`
Standard `E.M.F` experienced by the person with dental filing is:

Options

A. `+2.89V`
B. `-2.89V`
C. `-0.93V`
D. `+0.43V`

Explanation

To find the standard EMF experienced by a person with a dental filling when aluminum comes in contact with it, we can follow these steps:

### Step 1: Identify the half-reactions
In this scenario, we have two half-reactions:
1. **Oxidation at the anode (Aluminum)**:
\[ \text{Al} \rightarrow \text{Al}^{3+} + 3e^- \]
2. **Reduction at the cathode (Oxygen)**:
\[ \text{O}_2 + 4e^- + 4\text{H}^+ \rightarrow 2\text{H}_2\text{O} \]

### Step 2: Write the standard reduction potentials
From the question, we have the following standard reduction potentials:
- For aluminum:
\[ E^\circ_{\text{Al}^{3+}/\text{Al}} = -1.66 \, \text{V} \]
- For oxygen:
\[ E^\circ_{\text{O}_2/\text{H}_2\text{O}} = +1.23 \, \text{V} \]

### Step 3: Calculate the standard EMF
The standard EMF (E) of the galvanic cell can be calculated using the formula:
\[ E = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} \]
Here, the cathode is where the reduction occurs (Oxygen), and the anode is where the oxidation occurs (Aluminum).

Substituting the values:
\[ E = E^\circ_{\text{O}_2/\text{H}_2\text{O}} - E^\circ_{\text{Al}^{3+}/\text{Al}} \]
\[ E = 1.23 \, \text{V} - (-1.66 \, \text{V}) \]
\[ E = 1.23 \, \text{V} + 1.66 \, \text{V} \]
\[ E = 2.89 \, \text{V} \]

### Conclusion
The standard EMF experienced by the person with a dental filling is **2.89 V**.

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