In a Daniell Cell

A. Current flows from zinc electrode to copper electrode

B. Electrons flow from zinc electrode to copper electrode

C. Cell potential depends on size of electrodes used.

D. Electrons flow from copper electrode to zinc electrode.

E. Copper ions move towards cathode and zinc ions move away from anode

Choose the correct answer from the options given below:

B and E only

The correct answer is option 4. B and E only.

Let us delve into the functioning of a Daniell cell to understand why each statement is correct or incorrect:

A Daniell cell is a type of galvanic cell where chemical energy is converted into electrical energy through redox reactions. It consists of two half-cells connected by a salt bridge or porous membrane.

Components:

Zinc Electrode (Anode): Zinc metal undergoes oxidation here.

Copper Electrode (Cathode): Copper ions in solution undergo reduction here.

Salt Bridge: Maintains electrical neutrality by allowing the movement of ions between the two half-cells.

Redox Reactions:

Oxidation at the Anode:

\(\text{Zn (s)} \rightarrow \text{Zn}^{2+} (\text{aq}) + 2e^- \)

Zinc metal loses electrons (oxidized) and forms zinc ions.

Reduction at the Cathode:

\(\text{Cu}^{2+} (\text{aq}) + 2e^- \rightarrow \text{Cu (s)} \)

Copper ions gain electrons (reduced) and form copper metal.

Analysis of Statements

A. Current flows from zinc electrode to copper electrode

The statement is incorrect. Current in an external circuit flows from the positive terminal (cathode) to the negative terminal (anode). In a Daniell cell, the copper electrode is the positive terminal (cathode), and the zinc electrode is the negative terminal (anode). Hence, current flows from the copper electrode to the zinc electrode through the external circuit, not from zinc to copper.

B. Electrons flow from zinc electrode to copper electrode

The statement is correct. Electrons are released at the zinc electrode during oxidation and travel through the external circuit to the copper electrode, where they are consumed in the reduction reaction. This flow of electrons is what generates electrbic current in the external circuit.

C. Cell potential depends on the size of electrodes used

The statement is incorrect. The cell potential (or electromotive force, EMF) of a Daniell cell is determined by the difference in electrode potentials of the two half-cells, not by the size of the electrodes. The size of the electrodes affects the rate of reaction and the amount of substance that reacts, but not the fundamental cell potential.

D. Electrons flow from copper electrode to zinc electrode

The statement is incorrect. Electrons actually flow from the zinc electrode to the copper electrode. The zinc electrode is the source of electrons (anode), and the copper electrode is the destination for electrons (cathode)

E. Copper ions move towards the cathode and zinc ions move away from the anode

The statement is correct.  In the Daniell cell:

Copper ions (\(Cu^{2+}\)) in the solution move towards the copper electrode (cathode) to gain electrons and form copper metal. Zinc ions (\(Zn^{2+}\)) are formed at the zinc electrode (anode) and dissolve into the solution, moving away from the anode as zinc metal is oxidized to zinc ions.

Summary:

B. Electrons flow from zinc electrode to copper electrode: Correct because electrons are released at the zinc electrode (anode) and flow to the copper electrode (cathode).

E. Copper ions move towards the cathode and zinc ions move away from the anode: Correct because copper ions are reduced at the cathode and zinc ions are released into the solution from the anode.

Therefore, the correct answer is: Option 4: B and E only.