Unit 6 - Redox Reactions

Question 1

Describe oxidation (in terms of electrons)

Answer 1

Loss of electrons from an atom, ion or molecule

Question 2

Describe reduction (in terms of electrons)

Answer 2

Gain of electrons by an atom, ion or molecule

Question 3

Describe a redox reaction

Answer 3

A reaction in which oxidation and reduction take place at the same time

Question 4

Describe a half equation

Answer 4

An equation which shows either oxidation or reduction only

Question 5

Describe the relationship between oxidation number and how oxidised a substance is.

Answer 5

The more positive the oxidation number, the more oxidised a substance is (the more negative the oxidation number, the more reduced a substance is)

Question 6

What is the oxidation number for an element?

Answer 6

Zero

Question 7

Describe rules for positive oxidation numbers

Answer 7

Group 1 = +1, Group 2 = +2, Hydrogen = +1 (except in metal hydrides =-1)

Question 8

Describe rules for negative oxidation numbers

Answer 8

Fluorine = -1, Oxygen = -2 (except in peroxides = -1 and Fluorine Oxide = +2)

Question 9

Define an oxidising agent

Answer 9

A substance that brings about oxidation by removing electrons from another atom or ion

Question 10

Define a reducing agent

Answer 10

A substance that brings about reduction by donating electrons to another atom or ion

Question 11

Describe the 4 steps in constructing equations using oxidation numbers

Answer 11

1. Identify oxidation number changes. 2. Balance oxidation number changes. 3. Balance charges. 4. Balance atoms.

Question 12

Define disproportionation

Answer 12

The simultaneous oxidation and reduction of the same species in a chemical reaction