Module 2 - Redox

Question 1

What is an oxidation number?

Answer 1

The number of electrons an atom uses to
bond with any other atom

Question 2

What is the oxidation number
of an uncombined element
such as C, H, O2
?

Answer 2

0

Question 3

What is the oxidation number
of combined oxygen such as
in H2O?

Answer 3

-2

Question 4

What is the oxidation number
of oxygen in peroxides?

Answer 4

-1

Question 5

What is the oxidation number
of combined hydrogen such as
in NH3, H2S?

Answer 5

+1

Question 6

What is the oxidation number
of combined hydrogen in metal
hydrides such as LiH?

Answer 6

-1

Question 7

What is the oxidation number
of a simple ion?

Answer 7

Charge on the ion
E.g Na+→ +1 ; Cl- → -1

Question 8

What is the oxidation number
of combined fluorine such as
in NaF, CaF2
?

Answer 8

-1, -2

Question 9

When an element has more
than one stable oxidation
number how is it indicated?

Answer 9

Written as a Roman numeral

Question 10

What is the oxidation number
of Fe in iron (III) chloride?

Answer 10

+3

Question 11

What are oxyanions?

Answer 11

Negative ions that have an element
along with oxygen

Question 12

What is the oxidation number
of S in SO4
2-?

Answer 12

+6
Because, combined oxygen has an oxidation number of -2.
4 x -2 = -8.
The charge on the compound is -2. Sum of oxidation numbers must
equal -2
So, -2 -(-8) = +6

Question 13

Define oxidation in terms of
electron transfer and oxidation
number

Answer 13

Oxidation is
● Loss of electrons
● An increase in oxidation number

Question 14

Define reduction in terms of
electron transfer and oxidation
number

Answer 14

Reduction is
● Gain of electrons
● A decrease in oxidation number

Question 15

What is a redox reaction?

Answer 15

A reaction in which both oxidation and
reduction takes place

Question 16

What is the oxidation number
of a metal?

Answer 16

0, because it is an uncombined element