Oxidation, Reduction and Redox equations

Question 1

What is oxidation?

Answer 1

The loss of electrons
/Gain of Oxygen
/Loss of Hydrogen

Question 2

What is reduction?

Answer 2

The gain of electrons
/Loss of Oxygen
/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 equation for:

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.

Question 7

What is the oxidation

state of oxygen in OF2?

Answer 7

[O] = +2

Question 8

What is the oxidation

state of hydrogen in KH ?

Answer 8

[H] = -1

Question 9

What is the oxidation state of chlorine in NaClO ?

Answer 9

[Cl] = +1

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

[N] = -3

Question 13

What is the oxidation state of arsenic in AsO43- ?

Answer 13

[As] = +5

Question 14

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

Answer 14

[Fe] = +2

Question 15

Why is 1s22s22p5 a weaker reducing agent than 1s22s22p63s23p64s2 ?

Answer 15

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

Question 16

What happens in a redox reaction.

Answer 16

Electrons are transferred from one species to another.

One element is oxidised whilst another is reduced.

Question 17

Why is, 2CrO42- + 2H+ → Cr2O72- + H2O,

not a redox reaction?

Answer 17

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