A cell is prepared by dipping copper rod in 1M copper suphate solutoin and zinc rod in 1M `ZnSO_(4)` solution The standard reduction potential s of copper and zinc are + 0.34 and -0.76 V respectively
(i) what is the cell reaction ?
(ii) what will be the standsard electromotive force (EMF) of the cell ?
(iii) which electrode will be positive ?
(iv) How will the cell be represented ?

Answer

To solve the problem step by step, we will address each part of the question systematically.

### Step 1: Identify the Cell Reaction

We have two half-reactions based on the standard reduction potentials given:

1. **Copper Reduction (Cathode Reaction)**:
\[ \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \quad (E^\circ = +0.34 \, \text{V}) \]

2. **Zinc Oxidation (Anode Reaction)**:
\[ \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \quad (E^\circ = -0.76 \, \text{V}) \]

Now, we combine these two half-reactions to get the overall cell reaction. The electrons lost in the oxidation of zinc will be equal to the electrons gained in the reduction of copper:

\[ \text{Cu}^{2+} + \text{Zn} \rightarrow \text{Cu} + \text{Zn}^{2+} \]

### Step 2: Calculate the Standard Electromotive Force (EMF) of the Cell

The standard EMF of the cell can be calculated using the formula:
\[ E^\circ_{\text{cell}} = E^\circ_{\text{cathode}} - E^\circ_{\text{anode}} \]

Substituting the values:
\[ E^\circ_{\text{cell}} = (+0.34 \, \text{V}) - (-0.76 \, \text{V}) = 0.34 \, \text{V} + 0.76 \, \text{V} = 1.10 \, \text{V} \]

### Step 3: Identify the Positive Electrode

In an electrochemical cell, the cathode is where reduction occurs and is the positive electrode. Since copper is being reduced, the copper electrode is the cathode, and thus it is the positive electrode.

### Step 4: Represent the Cell

The cell can be represented in the following notation:
\[ \text{Zn} | \text{Zn}^{2+} \, (1M) || \text{Cu}^{2+} \, (1M) | \text{Cu} \]

Here, the left side represents the anode (zinc), and the right side represents the cathode (copper). The double vertical line (||) indicates the salt bridge separating the two half-cells.

### Summary of Answers

(i) **Cell Reaction**:
\[ \text{Cu}^{2+} + \text{Zn} \rightarrow \text{Cu} + \text{Zn}^{2+} \]

(ii) **Standard EMF of the Cell**:
\[ 1.10 \, \text{V} \]

(iii) **Positive Electrode**:
Copper (Cathode)

(iv) **Cell Representation**:
\[ \text{Zn} | \text{Zn}^{2+} \, (1M) || \text{Cu}^{2+} \, (1M) | \text{Cu} \]