9.4 Electrochemical Cells

Question 1

What are the two types of electrochemical cells?

Answer 1

Voltaic (galvanic) cells and electrolytical cells.

Question 2

What is electrolysis?

Answer 2

The break-in down of a substance in molten state or solution by the passage of electricity through it.

Question 3

What is the anode?

Answer 3

Electrode at which oxidation occurs.

Question 4

What is the cathode?

Answer 4

Electrode at which reduction occurs.

Question 5

What is the overall reaction in a voltaic cel?

Answer 5

Zn (s) + Cu2+ (aq) —–> Zn2+ (aq) + Cu (s)

Question 6

What is the cell convention of a voltaic cell?

Answer 6

Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)

Question 7

How does a voltaic cells convert energy?

Answer 7

Converts chemical energy from a spontaneous exothermic process to electrical energy.

Question 8

What is the anode and cathode in a voltaic cell?

Answer 8

Anode is NEGATIVE and cathode is POSITIVE.

Question 9

What happens to the more reactive metal in a voltaic cell?

Answer 9

It is always oxidised at the anode.

Question 10

How do the electrons flow in a voltaic cell?

Answer 10

Electrons flow from the more reactive metal through the external circuit to the ion of the less reactive metal. Electrons flow from the anode to the cathode.

Question 11

What happens at the cathode in a voltaic cell?

Answer 11

The ion of the less reactive metal is reduced at the cathode.

Question 12

Why is a salt bridge necessary in a voltaic cell?

Answer 12

The salt bridge completes the circuit and allows ions to flow into and out of the half cell. Ions move in the solution and the salt bridge.

Question 13

What can the salt bridge be made from?

Answer 13

A piece of paper soaked in a solution of an ionic salt such as KCl (aq).

Question 14

What determines the voltage in a voltaic cell?

Answer 14

The bigger the difference in reactivity between the metals the bigger the voltage.

Question 15

What is the overall reaction in a electrolytic cell?

Answer 15

PbBr2 (l) ——> Pb (l) + Br2 (g)

Question 16

How is energy converted in an electrolytic cell?

Answer 16

Converts electrical energy to chemical energy by forcing a non spontaneous reaction to occur.

Question 17

What is the anode and cathode in an electrolytic cell?

Answer 17

Anode is POSITIVE and cathode is NEGATIVE.

Question 18

What is oxidised at the anode in an electrolytic cell?

Answer 18

The negative ion is oxidised at the anode.

Question 19

How do the electrons flow in an electrolytic cell?

Answer 19

Electrons flow from the battery to the negative electrode (cathode) and from the positive electrode (anode) to the battery.

Question 20

What is reduced at the cathode in an electrolytic cell?

Answer 20

The positive ions is reduced at the cathode.

Question 21

How do ions move in an electrolytic cell?

Answer 21

Ions move in the electrolyte and electrons flow in the external circuit.

Question 22

How can electricity flow in the electrolytic cell?

Answer 22

The salt must be molten for electricity fro flow when molten the ions are free to move if it is sold then ions are not free to move.

Question 23

What are the products of electrolysis of a molten salt?

Answer 23

The elements which is it made up of.

Question 24

What does the cell convention for voltaic cells show?

Answer 24

It describes the overall reaction, a single line represent a phase boundary and the delve line is the salt bridge. The reaction at the anode is shown on the left (oxidation) and the reaction at the cathode (reduction) on the right.