1.7 Redox

Question 1

What is oxidation

Answer 1

Loss of electrons
Gain of oxygen
Loss of hydrogen

Question 2

What is reduction

Answer 2

Gain of electrons
Loss of oxygen
Gain of hydrogen

Question 2

What is an oxidising agent

Answer 2

Species that gains electrons

Question 2

What is a reducing agent

Answer 2

Species that lose electrons

Question 2

What are the half equations and ionic equation for
SnO + Zn –> ZnO + Sn

Answer 2

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

Ionic
Sn2+ + Zn –> Sn + Zn2+

Question 3

Define oxidation state

Answer 3

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

Question 4

What is the oxidation state of oxygen in OF2

Answer 4

+2

Question 5

What is the oxidation state of hydrogen in KH

Answer 5

-1

Question 6

What is the oxidation state of chlorine in NaClO

Answer 6

+1

Question 7

Define the term disproportionation

Answer 7

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

Question 8

What is the oxidation state of phosphorus in PCl5

Answer 8

+5

Question 9

What is the oxidation state of nitrogen in ammonia

Answer 9

-3

Question 10

What is the oxidation state of arsenic in AsO4 3-

Answer 10

+5

Question 11

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

Answer 11

+2

Question 12

Why is 1s2 2s2 2p5 a weaker reducing agent than 1s2 2s2 2p6 3s2 3p6 4s2

Answer 12

The 2p electron is closer to the nucleus than the 4s electron. The nuclear attraction is stronger so the 2p electron is lost less easily than the 4s electron

Question 13

What happens in a redox reaction

Answer 13

Electrons are transferred from one species to another
One element is oxidised whilst another is reduced

Question 14

Why is 2CrO4 2- + 2H+ –> Cr2O7 2- + H2O not a redox reaction

Answer 14

Chromium is oxidised whereas hydrogen remains the same oxidation state