Assigning Oxidation Numbers.notebook
May 17, 2016
Unit 13: Electrochemistry (Redox)
Aim: Assigning oxidation numbers in compounds.
Apr 13­1:10 PM
Optional to Copy
Why are electrons gained or lost by elements? Gaining electrons gives what type of charge?
Losing electrons gives what type of charge?
Where can we find the oxidation number for an element?
Apr 13­1:15 PM
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Assigning Oxidation Numbers.notebook
May 17, 2016
Reduction­oxidation reactions (Redox): a reaction where electrons are transferred from one substance to another.
Ex: Mg + 2 AgCl ­­> 2 Ag + MgCl2
Mg0 ­­> 2e­ + Mg+2 Mg was oxidized by losing 2 electrons.
Ag+ + 1e­ ­­> Ag0
Ag was reduced by gaining 1 electron.
"OIL RIG": Oxidation Is Losing e­, Reduction is Gaining e­.
In REDOX reactions one element MUST LOSE ELECTRONS and one element MUST GAIN THOSE ELECTRONS
Mar 28­8:34 PM
Rules for Assigning Oxidation Numbers
1) The TOTAL charge on a compound is zero and the total charge on a polyatomic ion is found in Table E. Ex: H2O has a total charge of 0.
Ex: ClO­1 has a total charge of ­1
2) Any free element alone has a charge of zero. Ex: H2, N2, Cu all have a charge of 0
Apr 13­1:16 PM
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Assigning Oxidation Numbers.notebook
May 17, 2016
3) If there is only one charge given in the table, use that charge
Ex: Group 1 Metals=+1
Group 2 metals=+2
Group 13 metals= +3
4) If there is a conflict as to which element will have the negative ox #, the more EN element will always win and be negative.
May 21­8:51 AM
Assigning oxidation numbers
1) MgSO4
Mg= +2
S= +6
O=­4
***THE SUM OF A
4) Ga
COMPOUND MUS
2) Mg(OH)2
Mg= +2
O= ­2
H=+1
5) NaCl
3) Ca(NO3)2
Ca= +2
N= +5
O= ­2
6) MgF
Apr 13­1:19 PM
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Assigning Oxidation Numbers.notebook
May 17, 2016
Assigning Oxidation Numbers
1. HCl
11. H2SO3
2. KNO3
12. H2SO4
3. OH­
13. BaO2
4. Mg3N2
14. KMnO4
5. KClO3
15. LiH
May 9­8:36 PM
Assigning Oxidation Numbers
6. Al(NO­3)3
16. MnO2
7. S8
17. OF2
8. H2O2
18. SO3
9. PbO2
19. NH3
10. NaHSO4
20. Na
May 9­8:36 PM
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