PMT 1.7 - Oxidation, Reduction and Redox equations Flashcards

What is oxidation?

What is oxidation?

●The loss of electrons

OR

●Gain of Oxygen (or any electronegative element)

OR

●Loss of Hydrogen (or any electropositive element)

What is reduction?

What is reduction?

●The gain of electrons

OR

●Loss of Oxygen (or any electronegative element)

OR

●Gain of Hydrogen (or any electropositive element)

What is an oxidising agent?

What is an oxidising agent?

Species that gains electrons.

What is a reducing agent?

What is a reducing agent?

Species that lose electrons.

What are the half equations and the ionic equation for:

SnO + Zn → ZnO + Sn

What are the half equations and the ionic equation for:

SnO + Zn → ZnO + Sn

Half Equations:

●Sn2+ + 2e- → Sn

●Zn → Zn2+ + 2e-

Ionic Equation:

●Sn2+ + Zn → Sn + Zn2+

Define oxidation state.

Define oxidation state.

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.)

What is the oxidation state of oxygen in OF2 ?

What is the oxidation state of oxygen in OF2 ?

[O] = +2

(Otherwise [O] = -2 in most other compounds)

What is the oxidation state of hydrogen in KH?

What is the oxidation state of hydrogen in KH?

[H] = -1

([H] = -1 is for metal hydrides. Otherwise [H] = +1 in most other compounds)

What is the oxidation state of chlorine in NaClO?

What is the oxidation state of chlorine in NaClO?

[Cl] = +1

(Otherwise [Cl] = -1 in most other compounds. NaClO is formed in a disproportionation reaction.)

Define the term disproportionation?

Define the term disproportionation?

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

(e.g. See topic 2.3 - Group 7(17), the halogens for examples in Uses of Chlorine)

What is the oxidation state of phosphorus in PCl5 ?

What is the oxidation state of phosphorus in PCl5 ?

[P] = +5

What is the oxidation state of nitrogen in ammonia?

What is the oxidation state of nitrogen in ammonia?

[N] = -3

(As ammonia is NH3)

What is the oxidation state of arsenic in AsO4^3- ?

What is the oxidation state of arsenic in AsO4^3- ?

[As] = +5

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

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

[Fe] = +2

Why is 1s22s22p5 a weaker reducing agent than 1s22s2 2p63s23p64s2 ?

Why is 1s22s22p5 a weaker reducing agent than 1s22s2 2p63s23p64s2 ?

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

What happens in a redox reaction.

What happens in a redox reaction.

●Electrons are transferred from one species (element) to another.

●One element is oxidised whilst another is reduced.

Why is,

2CrO42- + 2H+ → Cr2O7 2- + H2O

not a redox reaction?

Why is

2CrO42- + 2H+ → Cr2O7 2- + H2O

not a redox reaction?

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