Chapter 12: Electrochemistry

Question 1

____________ cells are contained systems in which redox reactions occur.

Answer 1

electrochemical

Question 2

What are the 3 types of electrochemical cells?

Answer 2

1. Galvanic / voltaic cells
2. Electrolytic cells
3. Concentration cells

Question 3

All three types of electrochemical cells contain ____________, where redox takes place.

Answer 3

electrodes

Question 4

The electrode where oxidation occurs is called the ____________

Answer 4

anode

AN OX RED CAT

Question 5

The electrode where reduction occurs is called the ____________

Answer 5

cathode

AN OX RED CAT

Question 6

The ____________ ________ corresponds to the voltage or electrical potential differene of the cell.

Answer 6

electromotive force (emf)

Question 7

If emf is positive, then the cell can do what? What does this mean?

Answer 7

The cell can release energy (∆G < 0); it is spontaneous

Question 8

If emf is negative, what does a cell have to do? What does this mean?

Answer 8

The cell must absorb energy (∆G > 0), which means it is nonspontaneous

Question 9

For all electrochemical cells, which direction do electrons move? Which way does the current run?

Answer 9

Electrons move from anode to cathode; current runs from cathode to anode

Question 10

All nonrechargeable batteries you own are ____________ cells, also called ________ cells.

Answer 10

galvanic; voltaic

Question 11

Because household batteries are used to supply energy to a flashlight or remote control, the reactions in these galvanic cells must be ____________

Answer 11

spontaneous

Question 12

Free energy change and electromotive force always have (opposite/same?) signs.

Answer 12

opposite

Question 13

In a galvanic cell, 2 electrodes of distinct chemical identity are placed in separate compartments, which are called ________-________. They are connected by a ________________ material..

Answer 13

half-cells; conductive

Question 14

Surrounding each of a galvanic cell’s electrodes is an aqueous ____________ solution composed of cations and anions.

Answer 14

electrolyte

Question 15

Connecting the two half-cell solutions of a galvanic cell is a ________ ________

Answer 15

salt bridge

Question 16

When the electrodes are connected to each other by a conductive material, charge will begin to flow - why?

Answer 16

the redox reaction taking place between the 2 half cells

Question 17

What do we accomplish by separating redox half-reactions into 2 compartments?

Answer 17

You can harness the energy and use it to do work by connecting various electrical devices into the circuit between the 2 electrodes

Question 18

What would happen if there were no salt brdige?

Answer 18

If there were only a wire, the reaction would stop quickly because an excess positive charge would build up on the anode and excess negative charge on the cathode. It would create a countervoltage.

Question 19

What does the salt bridge accomplish?

Answer 19

It permits the exchange of cations and anions. It has an inert electrolyte, which contains ions that will not reat with the electrodes or with the ions in solution.

Question 20

While anions from the salt birdge (Cl-) diffuse into the solution on the anode side (ZnSO4) to balance out the charge of the newly created Zn2+ ions, the cations of the salt bridge (K+) flow into the solution on the cathode side (CuSO4) to balance out the charge of the sulfate ions left in solution when the Cu2+ ions are reduced to Cu and precipitate onto the electrode. This is called ____________ or ________________.

Answer 20

plating, galvanization