Redox reactions
This presentation is the property of its rightful owner.
Sponsored Links
1 / 23

Redox Reactions PowerPoint PPT Presentation


  • 96 Views
  • Uploaded on
  • Presentation posted in: General

Redox Reactions. Chapter 18. + O 2 . Oxidation-Reduction (Redox) Reactions. “redox” reactions: rxns in which electrons are transferred from one species to another oxidation & reduction always occur simultaneously we use OXIDATION NUMBERS to keep track of electron transfers.

Download Presentation

Redox Reactions

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Redox reactions

Redox Reactions

Chapter 18

+ O2


Oxidation reduction redox reactions

Oxidation-Reduction (Redox) Reactions

  • “redox” reactions: rxns in which electrons are transferred from one species to another

  • oxidation & reduction always occur simultaneously

  • we use OXIDATION NUMBERS to keep track of electron transfers


Rules for assigning oxidation numbers

Rules for Assigning Oxidation Numbers:

1) the ox. state of any free (uncombined) element is zero.

  • Ex: Na, S, O2, H2, Cl2, O3


Rules for assigning oxidation numbers1

Rules for Assigning Oxidation Numbers:

2) The ox. state of an element in a simple ion is the charge of the ion.

Mg2+ oxidation of Mg is +2


Rules for assigning oxidation numbers2

Rules for Assigning Oxidation Numbers:

  • 3) the ox. # for hydrogen is +1

    (unless combined with a metal, then it has an ox. # of –1)

    Ex: NaOH (H bonded to O) v. NaH (H bonded to Na)


Rules for assigning oxidation numbers3

Rules for Assigning Oxidation Numbers:

4) the ox. # of fluorine is always –1.


Rules for assigning oxidation numbers4

Rules for Assigning Oxidation Numbers:

5) the ox. # of oxygen is usually –2.

Why USUALLY? Not -2 when it’s in a peroxide, such as hydrogen peroxide:

H2O2


Rules for assigning oxidation numbers5

Rules for Assigning Oxidation Numbers:

6) in any neutral compound, the sum of the oxidation #’s = zero.


Rules for assigning oxidation numbers6

Rules for Assigning Oxidation Numbers:

7) in a polyatomic ion, the sum of the oxidation #’s = the overall charge of the ion.


Rules for assigning oxidation numbers7

Rules for Assigning Oxidation Numbers:

**use these rules to assign oxidation #’s; assign known #’s first, then fill in the #’s for the remaining elements:


Examples assign oxidation s to each element

Examples: Assign oxidation #’s to each element:

a) NaNO3


Examples assign oxidation s to each element1

Examples: Assign oxidation #’s to each element:

b) SO32-


Examples assign oxidation s to each element2

Examples: Assign oxidation #’s to each element:

c) HCO3-


Examples assign oxidation s to each element3

Examples: Assign oxidation #’s to each element:

d) H3PO4


Examples assign oxidation s to each element4

Examples: Assign oxidation #’s to each element:

e) Cr2O72-


Examples assign oxidation s to each element5

Examples: Assign oxidation #’s to each element:

f) K2Sn(OH)6


Definitions

Definitions

  • Oxidation: the process of losing electrons (ox # increases)

  • Reduction: the process of gaining electrons (ox # decreases)

  • Oxidizing agents: species that cause oxidation (they are reduced)

  • Reducing agents: species that cause reduction (they are oxidized)


To help you remember

To help you remember…

OIL RIG

  • Oxidation Is Loss

  • Reduction Is Gain


Are all rxns redox rxns

Are all rxns REDOX rxns?

  • a reaction is “redox” if a change in oxidation # happens; if no change in oxidation # occurs, the reaction is nonredox.


Examples

Examples

MgCO3MgO +CO2


Examples1

Examples

Zn + CuSO4 ZnSO4 + Cu


Examples2

Examples

NaCl + AgNO3 AgCl + NaNO3


Examples3

Examples

CO2 + H2O  C6H12O6 + O2


  • Login