Electrochemical Cell

Q. Equinormal solution of two weak acids , HA(pKa= 3) and HB (pKb = 5) are each placed in contact with standard hydrogen electrode at 25oC. When a cell is construsted by interconnecting them through a salt bridge , find the emf of the cell.

Q. Why cant electrons flow through salt bridge in an electrochemical cell?

Q. What is the work of salt bridge?

1. Maintains the electric neutrality in internal circuit.
2. It transfers the electrons from negative rod to positive rod.
3. Cools down the cell by injecting ions into electrolytes.
4. It accelerates the equilibrium.

Q.

[BHU 1981]

1. Reduction occurs at the anode

2. Chemical energy is converted to light energy

3. Reduction occurs at the copper cathode

4. Oxidation occurs at the copper cathode

Q.

Which of the following is FALSE regarding the salt bridge used in voltaic cells? The salt bridge:

1. allows two half-cells to be separated

2. allows mixing of the two electrode solutions

3. maintains electrical neutrality in half cells

4. allows ions to cross over slowly

Q. In the experiment set up for the measurement of EMF of a half cell using a reference electrode and a salt bridge, when the salt bridge is removed, the voltage

1. Does not change
2. Decreases to half the value
3. Increase to maximum
4. Drops to zero

Q. Which of the following is true for electrochemical Daniel cell?

1. Electrons flow from copper electrode to zine electrode
2. Cations move towards copper electrode
3. Cations move towards copper electrode
4. Current flows from zinc electrode to copper electrode

Q. Which of the following conversion takes place in a galvanic cell?

1. Electrical energy to chemical energy
2. Chemical energy to electrical energy
3. Chemical energy to mechanical energy
4. Mechanical energy to chemical energy

Q.

The polarisation takes place in a simple voltaic cell on account of the deposition of

1. atomic hydrogen on zinc plate

2. atomic hydrogen on copper

3. molecular hydrogen on zinc plate

4. molecular hydrogen on copper plate

Q. What is cell representation ? Represent the reactions in dry cell and Daniell cell.

Q.

Assertion : Salts like $KCl,KN{O}_3$ i.e., inert electrolytes are used in salt bridge.

Reason : An inert electrolyte can easily be filled in the U-tube.

1. If assertion is true but reason is false.
2. If the assertion and reason both are false.
3. If both assertion and reason are true and the reason is the correct explanation of the assertion.
4. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Q. In a galvanic cell, the salt-bridge

1. does not participate chemically in the cell reaction
2. facilitates the diffusion of ions from one electrode to another
3. is necessary for the occurrence of the cell reaction
4. ensures mixing of the two electrolytic solutions.

Q. What is the work of salt bridge?

1. Maintains the electric neutrality in internal circuit.
2. Cools down the cell by injecting ions into electrolytes.
3. It accelerates the equilibrium.
4. It transfers the electrons from negative rod to positive rod.

Q.

When the sample of copper with zinc impurity is to be purified by

electrolysis, the appropriate electrodes of cathode and anode are

[AIEEE 2002]

1. Pure zinc, Pure copper

2. Impure sample, Pure copper

3. Impure zinc, Impure sample

4. Pure copper, Impure sample

Q. Two metal rods A, B are dipped is their ionic solutions respectively.
Following reactions happen at each electrode
$A\to A^{2+}+2e^{-}{B}^{2+}+2e^{-}\to B$
Which of these two rods acquire negative charge

1. A
2. B