Oxidation and Reduction 2

• Physics
• Secondary Education
• Age 12,13

15 March 2023

Chapter 10. Oxidation and Reduction

Content objectives

• Define redox reactions as involving simultaneous oxidation and reduction
• Define oxidation as the gain of oxygen and reduction as the loss of oxygen
• Use a Roman numeral to indicate the oxidation number of an element in a compound
• Identify redox reactions as reactions involving gain and loss of oxygen
• Identify oxidation and reduction in redox reactions
• Define oxidation in terms of: (a) loss of electrons ; (b) an increase in oxidation number
• Define reduction in terms of: (a) gain of electrons ; (b) a decrease in oxidation number
• Identify redox reactions as reactions involving gain and loss of electrons
• Identify redox reactions by changes in oxidation number using: (a) the oxidation number of elements in their uncombined state is zero ; (b) the oxidation number of a monatomic ion is the same as the charge on the ion; (c) the sum of the oxidation numbers in a compound is zero; (d) the sum of the oxidation numbers in anion is equal to the charge on the ion

Define redox reactions as involving simultaneous oxidation and reduction.

Define oxidation as the gain of oxygen and reduction as the loss of oxygen.

Oxidation

zinc oxide + carbon → zinc  + carbon monoxide

ZnO      +  C         →  Zn   +   CO

• gain of oxygen

Reduction

• loss of oxygen

 Identify redox reactions as reactions involving gain and loss of oxygen

 Identify oxidation and reduction in redox reactions

 Identify redox reactions as reactions involving gain and loss of oxygen

 Identify oxidation and reduction in redox reactions

Use a Roman numeral to indicate the oxidation number of an element in a compound

FeO       - Name: Iron (II) oxide

Fe2O3   - Name: Iron (III) oxide

CuCl2    - Name: Copper (II) chloride

CuCl    - Name: Copper (I) chloride

Define oxidation in terms of: (a) loss of electrons ; (b) an increase in oxidation number

Define reduction in terms of: (a) gain of electrons ; (b) a decrease in oxidation number

Oxidation Number 

• (also called oxidation state) is a number assigned to an atom or ion in a compound that indicates the degree of oxidation (or reduction)
• shows the number of electrons that an atom has lost, gained, or shared in forming a compound
• helps you to keep track of the movement of electrons in a redox process
• written as a +/- sign followed by a number (not to be confused with charge, which is written by a number followed by a +/- sign)

Define oxidation in terms of: (a) loss of electrons ; (b) an increase in oxidation number

Define reduction in terms of: (a) gain of electrons ; (b) a decrease in oxidation number

Oxidation

• loss of electrons

Reduction

• gain of electrons

Identify redox reactions as reactions involving the gain and loss of electrons

• zinc + copper sulfate → zinc sulfate + copper

• Zn     +  CuSO4               → ZnSO4            + Cu

• Zn(s) + Cu2+(aq) + SO42-(aq) →Zn2+(aq) + SO42-(aq) + Cu(s)

Remember:

• Spectator ions (those that do not change) are SO42-(aq). These can be removed, leaving behind the ionic equation.

• ionic equation:      Zn0(s) + Cu2+(aq) → Zn2+(aq) + Cu0(s)

What are the ionic half equations?

Identify redox reactions as reactions involving the gain and loss of electrons

• ionic equation:      Zn0(s) + Cu2+(aq) → Zn2+(aq) + Cu0(s)

What are the ionic half equations?

Practice

Plenary

What's next?