9.1

Question 1

Oxidation

Answer 1

Old definition: gain of oxygen; loss of hydrogen
New definition: loss of electron

Question 2

Reduction

Answer 2

Old definition: loss of oxygen; gain of hydrogen
New definition: gain of electron

Question 3

Oxidation state

Answer 3

value we assign to each atom in a compound that is a measure of control or possession it has relative to the atom in the pure element

Question 4

atoms in the free (uncombined) element have an oxidation state of

Answer 4

zero

Question 5

In simple ions, the oxidation state is

Answer 5

the same as the charge of the ion

Question 6

the oxidation states of all the atoms in a neutral (uncharged) compound must add up to

Answer 6

zero

Question 7

the oxidation states of all the atoms in a polyatomic ion must add up to

Answer 7

the charge of the ion

Question 8

the usual oxidation state for an element is

Answer 8

the same as the charge on its most common ion

Question 9

most of which elements have oxidation states that vary in different compounds

Answer 9

Main group non metals; the elements at the bottom of Group 14 and transition elements

Question 10

Usual oxidation state of Li, Na, K

Answer 10

+1

Question 11

Usual oxidation state of Mg, Ca

Answer 11

+2

Question 12

Usual oxidation state of F

Answer 12

-1; no exceptions because F is the most electronegative element

Question 13

Usual oxidation state of O

Answer 13

-2
Exceptions are
peroxides such as H2O2 where it is -1
OF2 where it is +2

Question 14

Usual oxidation state of H

Answer 14

+1
Exceptions are metal hydrides such as NaH where it is -1, this is due toe the fact that H is more electronegative that Na so it gains electron control

Question 15

Usual oxidation state of Cl

Answer 15

-1
exceptions are when it is combined with O or F because Cl is less electronegative that O and F so it loses electron control

Question 16

redox reaction

Answer 16

chemical reaction in which changes in the oxidation states occur

Question 17

Oxidation occurs when there is

Answer 17

an increase in oxidation state of an element

Question 18

Reduction occurs when there is

Answer 18

a decrease in oxidation state of an element

Question 19

Half equations

Answer 19

redox equation separated into equations for the oxidation and reduction processes

Question 20

summary of steps in writing redox equations

Answer 20

1. Assign oxidation states to determine which atoms are being oxidized and which are being reduced
2. Write half equations for oxidation and reduction as follows:
   a.balance the atoms other than H and O
   b.Balance each half equation for O by adding H2O as needed
   c. balance each half equation for H by adding H+ as needed
   d. balance each half equation for charge by adding electrons to the sides with the more positive charge
   e. check that each half equation is balanced for atoms and for charge
3. equalize the number of electronc in the two half equations by multiplying each appropriately
4. add the two half equations together, cancelling out anything that is the same on both sides.

Question 21

Oxidizing agent

Answer 21

substance that is being reduced

Question 22

reducing agent

Answer 22

substance that is being oxidized

Question 23

more reactive metals are

Answer 23

stronger reducing agents

Question 24

more reactive metal is able to

Answer 24

reduce the ions of a less reactive metal

Question 25

more reactive non metals are

Answer 25

stronger oxidizing agents

Question 26

redox titration

Answer 26

same technique
redox reaction
electrons are transferred from reducing agent to oxidizing agent

Question 27

activity series

Answer 27

list of metals (and C and H) in order of relative reducing agent strength

Question 28

winkler method

Answer 28

Method used to measure biological oxygen demand (BOD)

Question 29

BOD

Answer 29

quantity of oxygen needed to oxidize organiz matter in a sample of water over a five day period at a specified temperature