U5 Part 2

Question 1

Redox reactions are reactions in which _____ are transferred from one reactant to another

Answer 1

electrons

Question 2

All types of reactions are redox except _______ _______

Answer 2

double replacement

Question 3

oxidized

Answer 3

lose electrons

Question 4

reduced

Answer 4

gain electrons

Question 5

it is only a redox reaction when something is _____ and ______

Answer 5

oxidized, reduced

Question 6

The OS of any uncombined (free) element is __

Answer 6

0
ex. H2

Question 7

The OS of a monatomic ion equals the _____ of the _____

Answer 7

charge, ion
ex. K2S potassium has a charge of 1+, therefore its OS is +1 and sulfur has a charge of 2- therefore its OS is -2

Question 8

Monatomic ions are any ion combined on the _____ of the periodic table, anything on the back is ________

Answer 8

front, polyatomic

Question 9

Oxygen has an OS of ___ in a compound

Answer 9

-2
ex. MgO Mg has +2 and O has -2

Question 10

Peroxide has a charge of __
O2^2-

Answer 10

-1
ex. CaO2=calcium peroxide Calcium has a OS of +2 and O has a OS of -1
ex. H2O2=hydrogen peroxide Hydrogen has an OS of +1 and O has an OS of -1

Question 11

The OS of hydrogen in most of its compounds is ___ unless it is combined with a ____ in which case it is __.

Answer 11

+1, metal, -1

Question 12

The OS of fluorine in a compound is always ___

Answer 12

-1

Question 13

The other halogens have an oxidation number of ___ in most binary compounds. However, when halogens are combined with oxygen, they have _____ oxidation states.

Answer 13

-1, positive

Question 14

The sum of the OS of all atoms in a _____ compound is ___. The sum of the OS of all atoms in a polyatomic ion equals the charge of the ion.

Answer 14

neutral, 0

Question 15

it is possible that the _____ element can be reduced and oxidized in a reaction.

Answer 15

same

Question 16

oxidation half reactions: electrons are always on the _____ side, where electrons are ____

Answer 16

product, lost

Question 17

reduction half reactions: electrons are always on the _____ side, where electrons are ____

Answer 17

reactant, added

Question 18

when balancing half reactions, balance the ____ equation first.

Answer 18

full

Question 19

when balancing half reactions, the # of electrons for the oxidation and reduction equation must _____

Answer 19

match

Question 20

Electrochemistry

Answer 20

a branch of chemistry that deals with electricity-related applications of redox reactions
These reactions usually take place in an electrochemical cell

Question 21

Electrochemical cells: cathode is where _____ occurs
anode is where ____ occurs
electron flow: anode to cathode

Answer 21

reduction, oxidation

Question 22

Salt bridge

Answer 22

U shaped tube that contains electrolytes.
It balances the charges in the electrodes and allows electrons to flow without mixing the solutions
closes circuit

Question 23

Voltaic cell (type of electrochemical cell, also called galvanic cell)

Answer 23

redox reactions occurs spontaneously and produces electrical energy
ex. batteries and fuel cells

Question 24

in an electrochemical cell, when the battery runs out, cations and anions go in _____ directions in the ____ _____.

Answer 24

different, salt bridge

Question 25

in an electrochemical cell, when the battery is full, the cations and anions are flowing through the salt bridge ____

Answer 25

together.

They are next to each other.

Question 26

electrolytic cell (where elctrolysis occurs)

Answer 26

electrochemical cell where a redox reactions requires energy to occur - a nonspontaneous redox reaction
ex. charging batteries

Question 27

spontaneous proccesses

Answer 27

occurs on its own without any outside assistance.
ex. banana browns, nail rusts, apple falls to ground, fully charged battery

Question 28

nonspontaneous processes

Answer 28

wont take place unless it is “driven” by external energy
ex. cooking, photosynthesis, combustion

Question 29

oxygen gas is ____ during the corrosion of iron

Answer 29

reduced

Question 30

to prevent corrosion, coat things with other metals such as __, ___, and ___ (galvanizing).

Answer 30

Cr, Sn, Zn

Question 31

hydrogen ion (H+) ____ ___ the corrosion

Answer 31

speeds up