Electrochemistry

Question 1

redox reaction

Answer 1

is a reaction in ivolving the transfer of electrons

Question 2

oxidation

Answer 2

loss of electrons

Question 3

oxidation half reaction

Answer 3

half reaction where electrons are lost

Question 4

reduction

Answer 4

gain of electrons

Question 5

reduction half reaction

Answer 5

half reaction where electrons are gained

Question 6

reducing agent

Answer 6

-makes reduction take place
-substance that donates electrons

Question 7

oxidising agent

Answer 7

-makes oxidation take place
-substance that accepts electrons

Question 8

oxidation number

Answer 8

number that is allocated to every atom to keep track of the movement of electrons

Question 9

name the 2 types of redox reactions

Answer 9

spontaneous
non-spontaneous

Question 10

spontatneous reactions

Answer 10

-chemical energy is converted into electrical energy
-this occurs in a galvanic cell and it is a reaction that takes place without added energy

Question 11

non spontaneous reactions

Answer 11

-electrical energy is converted to chemical energy
-this occurs in a electrolytic cell

Question 12

Electrolysis

Answer 12

-chemical process in which electrical energy is converted to chemical energy
-the use of electric energy to produce a chemical change

Question 13

Electrolyte

Answer 13

• a substance that can conduct electricity by forming free ions when molten or dissolved in solution

Question 14

anode

Answer 14

electrode where oxidation takes place

Question 15

cathode

Answer 15

electrode where reduction takes place

Question 16

properties of reducing agents

Answer 16

-metal is strong RA
-The larger the metal atom, the stronger the RA it is
-e further away from the nucleus, and weaker
-undergoes oxidation quicker

Question 17

properties of oxidizing agents

Answer 17

-non-metal are strong OA
-The smaller the non-metal atom, the stronger the OA it is
-e closer away form a nucleus, and stronger
-undergoes reduction easier

Question 18

The salt bridge

Answer 18

To complete the circuit a salt bridge that contains a solution of an ionic salt (eg NaCl le KCl) joins the 2 solutions

Question 19

purpose of a salt bridge

Answer 19

it completes the circuit and maintains the electrical neutrality of the solutions by allowing ions to move between them.

Question 20

cell notation

Answer 20

• it summarizes the essential characteristics of a cell.

reducing agent /oxidized species //oxidizing agent/reduced species .

Question 21

emf

Answer 21

is the difference between the electrode potentials of the 2 half-cells

E cell=E(cathode)-E(anode)

Question 22

electrolytic cells vs galvanic cells

Answer 22

electrolytic
=need a battery
=electrical to chemical energy change
=non-spontaneous reaction
=endothermic reaction
=anode is positive
=cathode is negative

Galvanic cell
=is the battery
=chemical to electrical energy change
=spontaneous reaction
=exothermic reaction
=anode is negative
=cathode is positive

Question 23

electrolysis of a molten compound

Answer 23

= When ionic compounds melt, the ions are free to move and current can flow through the electrolyte.
= When a molten ionic compound through electrolyzed a metal always forms at a cathode and a non-metal always forms at the anode
=the electrolyte decomposes so electrical energy changes to chemical energy.

Question 24

name the type of elctrodes

Answer 24

= inert and active

Question 25

active electrodes

Answer 25

take part in the reaction. They are metals and their atoms can undergo oxidation at the anode to form metal ions

Question 26

inert electrodes

Answer 26

do not participate in the reaction, they simply transfer electrons between the ions and the battery.