Chemistry- Redox and Electrochemistry

Question 1

oxidation

Answer 1

• loss of electrons

- oxidation number/ state increases

Question 2

reduction

Answer 2

• gain of electrons

- oxidation number/ state decreases (reduces)

Question 3

oxidation state of pure elements

Answer 3

0

Question 4

more electronegative element

Answer 4

will have the negative oxidation state

Question 5

oxidation-reduction (redox) reactions

Answer 5

• any chemical process in which two elements undergo changes in oxidation number
• electrons are transferred from one element to another

Question 6

half-reactions

Answer 6

part of the reaction involving oxidation or reduction alone

Question 7

oxidation half reaction

Answer 7

electrons are the products

Question 8

reduction half reaction

Answer 8

electrons are reactants (R and R)

Question 9

prediction of spontaneity

Answer 9

higher metal must be oxidized and the higher nonmetal must be reduced (heat is produced)

Question 10

oxidizing agent

Answer 10

• reactants
• the entire compound, not only the element
• species in a reaction that is reduced

Question 11

reducing agent

Answer 11

• reactants
• the entire compound, not only the element
• species in a reaction that is oxidized

Question 12

electrochemistry

Answer 12

branch of chemistry that deals with electricity related applications of oxidation reduced reactions

Question 13

porous barrier/ salt bridge

Answer 13

• separates oxidation and reduction half reactions
• only ions can move through the barrier
• electrons are transferred through a conducting wire

Question 14

electrode

Answer 14

a conductor used to establish electrical contact with a non-metallic part of a circuit, such as an electrolyte

Question 15

half-cell

Answer 15

a single electrode immersed in a solution of its ions

Question 16

anode

Answer 16

• electrode where oxidation occurs (AN OX)
• Negative terminal on a battery
• electrons flow Away from the Anode and Closer to the Cathode

Question 17

cathode

Answer 17

• electrode where reduction occurs (RED CAT)

- positive (+) terminal on a battery

Question 18

voltaic cells

Answer 18

• uses spontaneous oxidation-reductions to convert chemical energy into electrical energy
• also called galvanic cells

Question 19

two types of voltaic cells

Answer 19

• batteries

- fuel cells

Question 20

voltage

Answer 20

• if positive, the reaction if spontaneous and energy is produced
• if negative, reaction is not spontaneous and energy is required

Question 21

electrolytic cell

Answer 21

• an electrochemical cell in which electrical energy is required to produce a redox reaction and bring about a chemical change
• connected to a battery

Question 22

electroplating

Answer 22

an electrolytic process in which a metal ions is reduced and a solid metal is deposited on a surface

Question 23

anode and cathode in electroplating

Answer 23

• anode is a plating metal

- cathode is the object to be plated (coated with a very thin layer of metal)

Question 24

rechargeable cells

Answer 24

• combines the chemistry of voltaic and electrolytic cells
• when a cell is powering device, it is behaving as a voltaic cell
• when a cell is plugged into a power source to charge, it is behaving as an electrolytic cell

Question 25

electrolysis

Answer 25

- electrical energy is used to force a non-spontaneous chemical reaction to occur - used to split water into H2 and O2 gas - used to separate metal from the minerals they are naturally found in

Question 26

types of electrolysis

Answer 26

- electrolysis of a (melted) salt - electrolysis of water - electroplating

Question 27

electrolysis of water

Answer 27

- O2 is the anode (oxidized) - H2 is the cathode (reduced) - overall: 2H2O --> 2H2 + O2

Question 28

electrolysis of salt

Answer 28

- nonmetal is anode | - metal is cathode

Question 29

charges of anode and cathode in electrolytic cells

Answer 29

- anode is now positive | - cathode is now negative