Determining Oxidation Numbers of KClO3, NH4+, Cr2O72-, MnO42-

[ipl]

Determine the oxidation numbers of the underlined elements in the following formulas:?
If you could explain each one, it would be greatly appreciated. Thanks!
a) KClO₃
b) NH₄₊
c) Cr₂O₇^2-
d) MnO₄^2-

 

[Borek]

Simple rules to follow to determine oxidation numbers. Try, then report.

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[ipl]

Okay is a) +5 because K=+1 and O=-2? I'm just wondering cause someone posted that on yahoo.

 

[Borek]

Yep, Cl in KClO₃ is +5 (regardless of what was posted on Yahoo).

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[ipl]

do you think you could explain to me why?

 

[Borek]

Because it can be calculated following rules from the page I have linked to?

Nothing magic about it. Molecule is neutral, K is +1 (one of the rules), O is -2 (one of the rules), so Cl+1+3*(-2)=0.

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methods