1.7 Oxidation, Reduction and Redox equation

Question 1

What is oxidation?

Answer 1

The loss of electrons

Or

Gain of oxygen

Or

Loss of Hydrogen

Question 2

What is reduction?

Answer 2

The gain of electrons

Or

Loss of oxygen

Or

Gain of hydrogen

Question 3

What is an oxidising agent?

Answer 3

Species that gains electrons

Question 4

What is a reducing agent?

Answer 4

Species that lose electrons

Question 5

What are the half equations and the ionic equations form

SnO + Zn —> ZnO + Sn

Answer 5

Half equations:
Sn2+ + 2e- —> Sn
Zn —> Zn2+ + 2e-

Ionic equation:
Sn2+ + Zn —> Sn + Zn2+

Question 6

Define oxidation state

Answer 6

A number which represents the number of electrons lost or gained by an atom of that element in the compound

(If electrons are lost number is positive, if electrons are gained number is negative)

Question 7

What is the oxidation state of oxygen in OF2?

Answer 7

+2

-2 in most other compounds

Question 8

What is the oxidation state of hydrogen in KH?

Answer 8

-1

+1 for most other compounds

Question 9

What is the oxidation state of chlorine in NaClO

Answer 9

+1

-1 in other compounds

Question 10

Define the term disproportionation?

Answer 10

Where in a redox reaction, the oxidation states of atoms of the same element, increase for some atoms, whereas decrease for some atoms

Question 11

What is the oxidation state of phosphorus in PCl5?

Answer 11

P = +5

Question 12

What is the oxidation state of nitrogen in ammonia?

Answer 12

-3

Question 13

What is the oxidation state of arsenic in AsO43-

Answer 13

+5

Question 14

What is the oxidation state of iron in K4Fe(CN)6?

Answer 14

+2

Question 15

What happens in a redox reaction

Answer 15

Electrons are transferred from one species (element) to another

One element is oxidised whilst another is reduced

Question 16

Why is

2CrO42- + 2H+ —> Cr2O72- + H2O,

Not a redox reaction

Answer 16

Chromium is oxidised whereas hydrogen remains the same oxidation state (no element is reduced)