Redox Reactions

Question 1

refers to a reaction in which a species gains electrons

Answer 1

reduction (GER)

Question 2

refers to a reaction in which a species gives up or loses electrons

Answer 2

oxidation (LEO)

Question 3

gets reduced during reaction

oxidizes something else–causes the species giving up the electrons to be oxidized

Answer 3

oxidizing agent

Question 4

Since electrons cannot be created or destroyed and there can be no isolated loss or gain of electrons, neither oxidation or reduction can occur _______, resulting in an electron transfer between 2 species

Answer 4

by itself

Question 5

The electrons released during ______ are taken up in the ______ process.

Answer 5

released during oxidation

taken up during reduction

Question 6

substance that gets oxidized
reduces something else
causes another species to be reduced

Answer 6

reducing agent

Question 7

an oxidizing agent get _______ and _____ electrons

Answer 7

reduced

gain electrons

Question 8

a reducing agent gets ______ and _____ electrons

Answer 8

oxidized

loses electrons

Question 9

the oxidation number of an element in its elemental form =

Ex: N2, O2, He, etc.

Answer 9

zero

Question 10

The oxidation state of a monatomic ion is the same as its ______

Answer 10

charge

Question 11

In molecules w/ 2 different elements, the elements w/ the greater ________ is assigned a negative oxidation number = to its charge in simple ionic compounds of the element

Answer 11

electronegativity

Question 12

Sum of the oxidation numbers = _____ for an electrically neutral compounds and equals the overall charge for an ionic species

Answer 12

zero

Question 13

Oxidation numbers for alkali metals (group I)

Answer 13

+1

Question 14

oxidation numbers for alkaline earth metals (group II)

Answer 14

+2

Question 15

oxidation number for group 3A

Answer 15

+3

Question 16

Oxidation number for halogens

Answer 16

-1 except when combo’ed w/ an element of high electronegativity

Question 17

Oxidation number for Oxygen

Answer 17

-2

Question 18

Oxidation number of Hydrogen when bonded to a more electronegative element (most nonmetals) =

Answer 18

+1

Question 19

Oxidation number of Hydrogen when bonded to a less electronegative element (most metals) =

Answer 19

-1

Question 20

a complex redox rxn can be separated into these component rxns
elements other than H and O should be balanced

Answer 20

half reactions

Question 21

in balancing REDOX rxns, the loss and gain of electrons is indicated where appropriate
charge is then balanced w _____ when in acid or _____ when in base. Elements O and H are then balanced with _____

Answer 21

H+: acid
OH-: base
H20: water

Question 22

each half-rxn is multiplied by an appropriate factor so that the number of electrons gained _______ those lost
rxns are then combined to form the net rxn

Answer 22

equal

Question 23

contained system in which a redox reaction occurs in conjuction with the passage of electric current
2 types: galvanic and electolytic

Answer 23

electrochemical cell

Question 24

2 types of electrochemical cell

Answer 24

galvanic (or voltaic)

electrolytic

Question 25

electrode at which oxidation occurs in an electrochemical cell (i.e. positive)

Answer 25

anode

Question 26

electrode at which reduction occurs in an electrochemical cell (i.e. negative)

Answer 26

cathode

Question 27

2 types of electrochemical cells
both contain two electrodes that serves as sites for oxidation and reduction half rxn
oxidation on the anode (loss of electrons)
reduction on the cathode (gain of electrons)

Answer 27

galvanic and electrolytic cells

Question 28

in REDOX rxn w/ exothermic and spontaneous half rxns (supply energy and are used to do work)
If only a wire were provided for electron flow b/w 2 electrochemical cells, rxn would stop bc an excess neg charge would build up in the sol’n surroundign the cathode and excess positive charge would build up in sol’n surrounding anode. This charge gradient is remedied by a _______, which permits the exchange fo cations and anions.

Answer 28

salt bridge

Question 29

this creates a charge gradient that permits the exchange of cations and anions in an electrochemical cell
contains an inert electrolyte
at the same time the anions from the salt bridge (Cl-) diffuse from this of the cell into the sol’n to balance out the charge of the newly created + ions and the cations of this flow into the other sol’n to balance out the charge of the neg ions left in solution

Answer 29

salt bridge

Question 30

common dry cell battery and the lead-acid storage battery found in cars

Answer 30

galvanic cells

Question 31

in an electrolytic cell w/ positive delta G and nonspontaneous, _______ is required to induce the reaction

Answer 31

electrical energy

Question 32

oxidation happens at the ____ of an electrolytic cell

Answer 32

anode

AN OX

Question 33

reduction happens at the ______ of an electrolytic cell

Answer 33

cathode

RED CAT

Question 34

electrons flow throguh the wire from the ________ to the ______ in an electrode

Answer 34

anode to the cathode

Question 35

the species in a rxn that will be oxidized or reduced can be determined from the ______ of each species, or the tendency of a species to acquire electrons and be reduced
measured in Volts
defined relative to the standard hydrogen electrode (0.0 volts)

Answer 35

reduction potential

SI Unit = volts

Question 36

the more positive the reduction potential, the ________ the species’ tendency to be reduced

Answer 36

greater

Question 37

reduction potential measured under standard conditions (25 degrees C, 1M concentration for each ion in the rxn, partial pressure of 1 atm for each gas in teh rxn, and metals in their pure state)

Answer 37

standard reduction potential (Ei)

Question 38

If a species has a large reduction potential, it likes to be reduced and is a strong ___________

Answer 38

oxidizing agent

Question 39

If a species has a large negative reduction potential, is does not like to undergo reduction, and the equation must be ______ for the rxn to become spontaneous (favored)

Answer 39

flipped

flip the sign on the reduction potential when the reaction is flipped

Question 40

calculated by standard reduction potentials

describes the difference in potential between two half-cells

Answer 40

Electromotive force (EMF or Ecell)

Question 41

Equation: Electromotive Force

Answer 41

EMF = Ered + Eox

Question 42

The standard EMF of a galvanic cell is ______

Answer 42

positive

Question 43

The standard EMF of an electrolytic cell is ______

Answer 43

negative

Question 44

When adding standard potentials, do not _______.

Answer 44

multiply by the number of moles oxidized or reduced