Ch. 11: Oxidation-Reduction Reactions

Question 1

Oxidation

Answer 1

Loss of electrons

Question 2

Reduction

Answer 2

Gain of electrons

Question 3

Oxidation Reduction Reactions

Answer 3

Pairing of oxidation and reduction

Question 4

Oxidizing agent

Answer 4

Facilitates the oxidation of another compound and is reduced itself in the process

Question 5

Reducing agent

Answer 5

Facilitates the reduction of another compound and is oxidized itself in the process

Question 6

Common oxidizing agents

Common reducing agents

Answer 6

Almost all contain oxygen or a similarly electronegative element
Often contain metal ions or hydrides (H-)

Question 7

Common oxidation states of representative elements:

Free element or diatomic species

Answer 7

0

Question 8

Monatomic ion

Answer 8

Charge of the ion

Question 9

Group IA metals

Answer 9

+1

Question 10

Group IIA metals

Answer 10

+2

Question 11

Group VIIA

Answer 11

-1, unless combined w an element w higher electronegativity

Question 12

Hydrogen

Answer 12

+1, unless it is paired w a less electronegative element, in which case it is -1

Question 13

Oxygen

Answer 13

Usually -2, except in peroxides (when the charge is -1) or in compounds w more electronegative elements

Question 14

Overall charge of a compound

Answer 14

Equal to the sum of the oxidation numbers of all of the atoms present in a compound

Question 15

Half-reaction method/ion electron method

Answer 15

Most common method for balancing redox rxns

• separate the 2 half rxns
• balance the atoms of each half-reaction. Start w all the elements besides H and O. in acidic solution, balance H and O using water and H+. In basic solution, balance H and O using water and OH-
• balance the charges of each half-reaction by adding electrons as necessary to one side of the reaction
• multiply the half reactions as necessary to obtain the same number of electrons in both half-reactions
• add the half-reactions, canceling out terms on both sides of the reaction arrow
• confirm that the mass and charge are balanced

Question 16

Complete ionic equation

Answer 16

Accounts for all of the ions present in a arxn. To write a complete ion rxn, split all aqueous compounds into their relevant ions. Keep solid salts intact

Question 17

Net ion equations

Answer 17

Ignore spectator ions to focus only on the species that actually participate in the rxn. To obtain a net ionic reaction, subtract the ions appearing on both sides of the reaction, which are called spectator ions

• for reactions that contain no aqeuous salts, the net ion eqation is generaly the same as the overall balanced rxn
• for double replacement (metathesis) reactions that do not form a solid salt, there is no net ionic reaction bc all ions remain in solution and do not change oxidation number

Question 18

Disproportionation (dismutation) reactions

Answer 18

A type of redox rxn in which one element is both oxidized and reduced, forming at least 2 molecules containing the element w diff exoidation states

Question 19

Oxidation reduction titrations

Answer 19

Similar in methodology to acid-base titrations. These titrations follow transfer of charge
- indicators used in such titrations change color when certain voltages of solutions are achieved

Question 20

Potentiometric titration

Answer 20

Form of redox titration in which a voltmeter or external cell measures the electromotive force (emf) of a solution. No indicator is used, and the equivalence point is determined by a change in voltage