Electrochemical Cells

Question 1

What is a salt bridge?

Answer 1

It is a junction used to connect the anodic and cathodic compartment in an electrochemical cell.

Question 2

What are the types of a salt bridge?

Answer 2

• a glass U-tube filled with electrolytes (NaCl, KCl, KNO3)
• filter paper or cotton soaked in electrolyte

Question 3

What are the functions of a salt bridge?

Answer 3

• To complete the circuit
• To permit the transfer of ions between the two compartments thus avoiding equilibrium
• To maintain electrical neutrality

Question 4

What is the electrode potential?

Answer 4

This is a measure of the tendency of an atom of the element of an electrode to undergo oxidation or reduction.

Question 5

What is the standard hydrogen electrode?

Answer 5

It is a reference electrode against which the electrode potentials of all electrodes are measured.

Question 6

How is a standard hydrogen electrode made?

Answer 6

A platinum electrode, covered with platinum black, is immersed in 1 mole of a H+ solution (such as HCl) at 25°C while H2 gas at 1atm is passed over it. While Platinum is inert, it permits the hydrogen gas to be absorbed on its surface.

Question 7

What is potential of a hydrogen electrode?

Answer 7

0v(volts)

Question 8

What is a fuel cell?

Answer 8

A fuel cell is a device that converts the chemical energy of a combustible fuel into electrical energy at lower temperature and without flame.

Question 9

What is the anodic reaction of a hydrogen-oxygen fuel cell?

Answer 9

2H2(g) + 4OH-(aq) ===> 4H2O(l) + 4e-

Question 10

What is the cathodic reaction in a hydrogen-oxygen fuel cell?

Answer 10

O2(g) + 2H2O(l) + 4e- ===> 4OH-

Question 11

What is the overall reaction of the hydrogen-oxygen fuel cell?

Answer 11

2H2(g) + O(g) ===> 2H2O(l)