Oxidation And Reduction

Question 1

Oxidation

Answer 1

(of an element) takes place when it loses electrons

Question 2

Reduction

Answer 2

(of an element) takes place when it gains electrons

Question 3

OILRIG stands for…

Answer 3

oxidation is loss
redcution is gain

Question 4

an oxidising agent

Answer 4

is a substance that brings about oxidation in other substances

Question 5

A reducing agent

Answer 5

is a substance that brings about reduction in other substances

Question 6

Rule for assigning oxidation number to: Oxygen

Answer 6

Oxi number= -2
2 exceptions: H2O2 = -1 because it is an unusual compound
OF2 = +2 because fluorine is more electronegative than oxygen

Question 7

Rule for assigning oxidation number to: Hydrogen

Answer 7

Oxi number = +1
Exceptions: metal hydroids (NaH, MgH2 etc) = -1
Reason: More electronegative than metals

Question 8

Rule for assigning oxidation number to: Uncombined elements

Answer 8

Oxi number = 0

Question 9

Rule for assigning oxidation number to: Simple ions

Answer 9

Cl-, Mg+2 etc Oxi number= charge on ion

Question 10

Rule for assigning oxidation number to: Halogens (Group 7)

Answer 10

Oxi number = -1
Unless bonded with a more electronegative element

Question 11

Rule for assigning oxidation number to: Compounds

Answer 11

The combined oxi numbers of all the elements = 0
H2SO4 -2 = 2+S-8=0 S= 6

Question 12

Rule for assigning oxidation number to: Complex ions

Answer 12

The sum of the oxi numbers add to the charge on the complex ion
SO4 -2= S+4(-2) = -2 S= 6

Question 13

If any situation doesn’t fit any of these rules…

Answer 13

Let the oxi number equal the charge on the ion the element would form ( K2PO4) O=-2 K is in group one so will lose one electron oxi number = +1 (2+P-8)= 0 P=6