Multiple oxidation states
This presentation is the property of its rightful owner.
Sponsored Links
1 / 8

Multiple Oxidation States PowerPoint PPT Presentation


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

Multiple Oxidation States. Truman Chemistry Dept. Oxidation States can change during a reaction. Example: Oxidation state of oxygen CH 4 + 2O 2  CO 2 + 2H 2 O In O 2 the oxidation state of O is zero In CO 2 and H 2 O the oxidation state of O is -2

Download Presentation

Multiple Oxidation States

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


Multiple oxidation states

Multiple Oxidation States

Truman Chemistry Dept.


Oxidation states can change during a reaction

Oxidation States can change during a reaction

  • Example: Oxidation state of oxygen

    • CH4 + 2O2 CO2 + 2H2O

      • In O2 the oxidation state of O is zero

      • In CO2 and H2O the oxidation state of O is -2

    • So the main question here is how can we predict how the oxidation state will change?

    • There are rules to predict this….


Rules

All elements in a diatomic molecule have an oxidation state of zero (they are neutral) ie. Cl2

If an element is monatomic (by itself) the charge is only as specified (ie. Cl-). Free elements have a charge of zero (ie. Fe)

All neutral compounds must have a net (total) oxidation charge of zero and the element with the highest electronegativity (furthest right on table) is the negative element.

Rules


Rules continued

Rules continued…

  • Hydrogen always has a +1 charge except in hydrides where it is negative one (ie. LiH or CaH2)

  • Oxygen always has a -2 charge except in peroxides (H2O2) where it is -1

  • Group 1 elements are normally +1

  • Group 2 elements are normally +2

  • Group 17 elements are often -1


Polyatomic ion rules

Polyatomic ion rules…

  • Polyatomic ions have a net charge that is equal to the sum of all the charges.


Lets try some

Lets try some:

  • 1. The oxidation number of nitrogen in N2 is (1) +1    (2) 0    (3) +3      (4) -3

  • What is the oxidation number of hydrogen in CaH2? 

    (1) +1     (2) +2      (3) -1     (4) -2

  • What is the oxidation number of carbon in NaHCO3? 

    (1) -2     (2) +2      (3) -4   (4) +4


A few more

A few more?

  • What is the oxidation number of chlorine in HClO4? (1) +1      (2) +5    (3) +3     (4) +7

  • What is the oxidation number of sulfur in H2SO4? (1) 0     (2) -2     (3) +6   (4) +4

  • What is the oxidation number of chromium in K2Cr2O7? (1) +12     (2) +2   (3) +3    (4) +6


Lets look at some reactions

Lets look at some reactions:

  • Al + O2 Al2O3

    • What happened to the oxidation states?

    • Half reactions?

  • S + NO3- SO2 + NO

    • What happened to the oxidation states?


  • Login